List of Koban Types and the Edo Monetary System
The koban minted throughout the Edo period are an important indicator that tells the story of Japan's economic history through their types and evolution. The ten major koban are the Keichō, Genroku, Hōei, Shōtoku, Kyōhō, Genbun, Bunsei, Tenpō, Ansei, and Man'en. In addition to these, locally minted pieces such as the Sado koban and Suruga koban also existed, resulting in an exceptionally diverse range of coins in circulation. Each koban reflects the political and economic conditions of the period in which it was minted, and possesses its own distinctive characteristics in gold fineness, weight, and the hallmarks (極印) stamped on the reverse. This diversity is an inexhaustible source of fascination for collectors. The koban served as the cornerstone of the san-ka seido (三貨制度)—the three-currency system of gold, silver, and copper established by the Edo shogunate—and was used particularly for high-value transactions and settlements between daimyo. Understanding the monetary system as a whole makes the value of koban all the more clear. We recommend first visiting System and Overview of Edo Gold Coins to gain an overview of Edo-period coinage.
The History of Koban and the Economic Background of Recoinage
The history of koban is closely tied to the changes in the shogunate's finances and economic policy. The early Keichō koban boasted a high fineness and stable value, but as the Genroku era arrived, the shogunate's financial difficulties led to frequent "recoinages" (改鋳) that reduced the gold fineness. This was a last-resort measure to increase the money supply and restore fiscal health. However, the decline in fineness often triggered price inflation and economic disorder. The Shōtoku recoinage under Arai Hakuseki attempted to restore the fineness to the level of the Keichō koban, but adjustments to gold fineness and weight continued through the Kyōhō, Genbun, and Tenpō eras in response to economic conditions. Behind each of these recoinages lay two constant imperatives: the shogunate's fiscal situation and the stabilization of the monetary economy. Each individual koban bears the imprint of the economic thinking and political intentions of its time.
Early Koban: From the High-Fineness Keichō Era to an Age of Fluctuating Fineness
Koban from the early Edo period are characterized by high fineness. The Keichō Koban (慶長小判) holds the highest position among Edo gold coins, with a gold fineness of 84.3% and a weight of 17.73g. Its stable value symbolized the solid economic foundations of the Tokugawa shogunate. However, the situation changed dramatically with the Genroku era. The Genroku Koban (元禄小判) saw a dramatic drop in fineness to 57.4%, driven by the shogunate's fiscal distress and a decline in gold and silver output. Because the minting period was short and surviving examples are few, these coins now trade at very high prices. The subsequent Hōei Koban (宝永小判) restored the fineness to approximately 84%, while halving the weight to 9g (catalog figure). In response to this, the Shōtoku Koban (正徳小判) was minted under the leadership of Arai Hakuseki, restoring the fineness to 84.3%. The following Kyōhō Koban (享保小判) also maintained a high fineness comparable to the Keichō koban, aiming to stabilize the monetary economy. This early period of koban can be described as an era in which shogunate policy was directly reflected in coinage. Further details can be explored at Keicho Koban.
Middle-Period Koban: Economic Growth and the Adjustment of Money Supply
Although the monetary economy appeared to have regained stability through the Kyōhō reforms, the middle period brought another wave of change. The Kyōhō Koban (享保小判) had a high fineness and high weight comparable to the Keichō koban and circulated for a long period. As a result, a relatively large number survive today, and its accessibility makes it popular among collectors. However, as the economy developed, a shortage of money supply became apparent, and the shogunate once again carried out a recoinage. The Genbun Koban (元文小判) had a fineness of 65.7% and a weight of 13.0g, reduced in both fineness and weight. This was a practical measure to increase the money supply and is evaluated as a policy response to economic growth. The subsequent Bunsei Koban (文政小判) had a fineness of 56.4% and is notable for the character "文" written in cursive script on the reverse. The koban of this period demonstrate that monetary policy was not merely about fiscal reconstruction, but also about adapting to the realities of the economy. The increase in circulation had a significant impact on commercial transactions even among ordinary people.
Late-Period Koban: The Turmoil of the Bakumatsu and the Response to the Opening of Japan
During the tumultuous Bakumatsu period, koban too underwent dramatic changes. The Tenpō Koban (天保小判), with a fineness of 56.8% and a weight of 11.2g, was the most widely circulated koban of the late Edo period. Because many survive today, well-preserved examples are relatively accessible, making it the ideal first koban for beginners. However, in the late 1850s, just before Japan opened its ports, the large-scale outflow of gold exploiting the difference in international gold-to-silver ratios became a serious problem. In response, the Ansei Koban (安政小判) was hastily minted, but its minting period was short, making it extremely rare. The decisive measure was the Man'en Koban (万延小判). It was drastically reduced in size to a weight of 3.32g, with a fineness also kept low at 56.8%. This was an emergency measure to stem the outflow of gold accompanying the opening of Japan, and it marks a major turning point in Japan's monetary history. The koban of this period vividly reflect the turbulent era in which they were produced.
Comparison of Koban by Gold Fineness, Weight, and Minting Period
Comparing the specifications of the major koban makes the historical significance of each recoinage clearer. The Keichō koban had a gold fineness of 84.3% and a weight of 17.73g, and was minted for approximately 110 years. The Genroku koban had a fineness of 57.4% and a weight of 17.82g, with a minting period of only 7 years. The Hōei koban had a fineness of approximately 84% and a weight of 9g (catalog figure), with a short-lived minting period. The Shōtoku koban, at a restored fineness of 84.3% and 17.75g, was minted for 2 years; the Kyōhō koban, also at 84.3% and 17.75g, was minted over approximately 90 years. The Genbun koban had a fineness of 65.7% and a weight of 13.0g and circulated for approximately 40 years; the Bunsei koban had a fineness of 56.4% and a weight of 13.0g for approximately 20 years. The late Edo Tenpō koban circulated with a fineness of 56.8% and a weight of 11.2g for approximately 20 years; the Ansei koban had a fineness of approximately 57% and a weight of 9g (catalog figure) for only 1 year. Finally, the Man'en koban was minted with a fineness of 56.8% and a weight of 3.32g for approximately 7 years. The transition in gold fineness moved in waves—84% → 57% → 84% → 65% → 57% → 57%—clearly reflecting the shogunate's fiscal situation and economic policy in numerical form. These figures are among the factors discussed at Five Factors That Determine Coin Value.
Hallmarks and Inscriptions: The Key to Identification and Authentication
The most important element in identifying the type of a koban is the "gokuin" (極印)—the hallmark stamped on the reverse. These are characters indicating the name of the Goto family, the head of the gold mint (金座), or the era name of the recoinage. For example, the Keichō koban bears the characters「光次」, derived from the name of Goto Mitsutsugu, who was responsible for the gold mint. The Genroku koban is stamped with the character「元」, and the Hōei koban with「永」. The Kyōhō koban bears「享」, the Genbun koban「文」, and the Tenpō koban is characterized by「保」and a paulownia crest. The Man'en koban shows the character「正」. These hallmarks are the first things to check when determining the authenticity and type of a koban. If a hallmark is indistinct or inconsistent with other features, there are grounds to suspect alteration or forgery. The paulownia crest on the obverse and the za-nin-in (座人印)—the personal stamp of the mint worker—are also important clues in authentication. Refer to Japanese Coin Counterfeit Detection Guide to sharpen your ability to observe fine details.
Current Market Price Ranges and Rarity Rankings
The market price of koban varies greatly depending on the rarity of the type, condition of preservation, and market demand. The following are reference market prices for examples grading from fine to choice fine. Keichō koban: 800,000–1,500,000 yen; Genroku koban: 1,200,000–3,000,000 yen; Hōei koban: 1,500,000–3,500,000 yen; Shōtoku koban: 800,000–1,800,000 yen; Kyōhō koban: 600,000–1,200,000 yen; Genbun koban: 500,000–1,000,000 yen; Bunsei koban: 400,000–800,000 yen; Tenpō koban: 300,000–800,000 yen; Ansei koban: 800,000–2,000,000 yen; Man'en koban: 200,000–500,000 yen. Types with short minting periods and few surviving examples—such as the Genroku, Hōei, and Ansei koban—tend to command higher prices. The Tenpō and Man'en koban, on the other hand, are relatively accessible and represent a price range suitable for beginners. These prices are reference figures only; in actual transactions, the condition of the individual piece and the presence or absence of authentication have a significant impact. Market prices can be read more deeply by understanding the concepts at Market Cycles in Ancient Coins.
Identifying Forgeries and Alterations and Managing Risk
In collecting koban, the risk of forgeries and altered pieces is something that must always be taken into account. The types most at risk of counterfeiting are high-value and rare pieces such as the Keichō, Genroku, and Ansei koban. Sophisticated forgeries of these koban are numerous, and distinguishing them without specialist knowledge is extremely difficult. The Tenpō and Kyōhō koban, having more surviving examples, are said to be comparatively easier to detect, but caution is still necessary. The Man'en koban, being small in size and low in the cost of forgery production, also tends to have crude fakes in circulation. To authenticate a koban, the basic steps are weight measurement, confirmation of gold fineness by X-ray fluorescence analysis, and microscopic examination of the yasuri-me (鑢目, file marks) and hallmarks. These three checks can eliminate the majority of forgeries, but ultimately authentication by a specialist is indispensable. Read Introduction to Identifying Counterfeits thoroughly to build your knowledge.
Utilizing Specialist Authentication Institutions and Grading Services
The use of specialist authentication institutions is indispensable for determining the authenticity and assessing the value of koban. In Japan, the Japan Numismatic Dealers Association (一般社団法人日本貨幣商協同組合, JNDA) plays a central role and provides highly reliable authentication. The authentication process begins with precise measurement of weight and dimensions, followed by confirmation of gold fineness by X-ray fluorescence analysis. The yasuri-me (file marks), hallmarks, and surface details are then examined under a microscope and compared against known reference materials, allowing a comprehensive judgment of authenticity and condition. In recent years, major overseas authentication institutions such as PCGS and NGC have also begun accepting Japanese antique coins, and grading and slab encapsulation by these institutions enhances the international marketability and credibility of koban. Since authenticated koban carry a significantly reduced risk of forgery, particularly when considering the purchase or investment in high-value pieces, we recommend understanding the criteria at Fundamentals of Grading and making active use of these services.