A Visit to the Japan Mint Museum in Osaka

The Japan Mint is located in city of Osaka, it is the third largest city after Tokyo and Kyoto. It was established on 4 April 1871, a time when there is no heavy industries to speak of in Japan. Everything needed to make coins were imported and all the raw materials were produced on site, which explains the size of the mint facility. The mint was also build next to the Okawa river, which joins the main Yodo river ((淀川) and flows into Osaka Bay. This allow ships to bring in to unload the materials needed for the mint.

Fig 1 : Facade of the Main Building

Fig. 1 : The Japan Mint Main Building from across the street
Fig. 2 : The Japan Mint Main Building from across the street

Fig 2 : Overlooking the Okawa River
Fig 2 : Overlooking the Okawa River with red and yellow autumn leaves
Tucked in nice corner of the mint, facing the Okawa river is the mint museum. It is a 3 story building complete with historical exhibits on the coinage of Japan. Below is a series of photos taken during my visit to the mint museum.

Fig 4 : The entrance to the mint museum behind the main building

Fig 6 : Scaled model of the entire Japan Mint, with the factories.

Fig 7 : The place must be at least 40 acres!

Fig 8 : The min museum building is the one with the green roof top

Fig 9 : Japanese coins from 1955 onwards

Fig 9 : Previous heads of the Japan Mint (Don't read Japanese, perhaps some of you who do can help me out here !)

Fig 10 : Heads of Japan Mint Part II

Fig 11 : Heads of Japan Mint Part III

Fig 12 : How the mint looked like back in the early days

The first Japan Mint engraver
Fig 13 : The first Japan Mint engraver

Fig 14 : Early proofs/trials of early Japanese coins

Fig 15: Early proofs/trials of early Japanese coins

Fig 16 : Early mint die, obverse and reverse

Fig 17 : Sketches of the coin design on paper

 The transfer reduction lathe or Javier machine which reduces the 8 to 10 inch design on to a Master Hub of the coin at 26.5mm in diameter
Fig 18 : The transfer reduction lathe or Javier machine which reduces the 8 to 10 inch design on to
a Master Hub of the coin at 26.5mm in diameter

Fig 19: The original 8 to 10 inch size model to be transferred
Fig 19: The original 8 to 10 inch size model to be transferred

Fig 20 : The comparison between the original (L) and the final sizes (R)

Fig 21 : The carving tip of the transfer reduction machine, made from hardened steel

This is the most interesting part is the coin minting process display where they illustrate in detail how a block of raw metal is turned into coins. The process is not much different from the US Mint process which I learnt in my diploma in numismatics with the American Numismatic Association (ANA). It is a 10 step process, as shown below :

Fig 22 : Step 1 &2  - Convert / press block metal in to sheets/coils

Fig 23 : Step 3 & 4 - Thinning the sheets to the required 2.0 mm for the 500 Yen coin

Fig 23 : Step 5 : Blanking - stamping the sheets to produce the blanks

Fig. 24 : Step 5  - Blanking process results - a close up shot
Fig 25 : Step 6 & 7 : Upsetting and annealing - the upsetting process raises the edge of the coin
and annealing reheats the blanks to harden it further.
Do you know why the edge of the coin is raised?

Fig 26 : Upsetting process up close - note the rim of the coin is higher than the interior of the coin
Fig 27 : The blanks after the annealing process
Fig 27 : Step 8 & 9 : Cleaning & Coin Press and final inspection - the blanks are then cleaned and sent
to the coin press machines that are installed with the obverse and reverse die and press
the blanks into coins with 100-200 tons of pressure depending on coin size and metal type.

Fig 28 : Cleaned blanks, ready to be pressed.
Fig 29 : The final product after the coin press - 500 Yen pieces
Fig 30 : Step 10 - Bagging and Tagging - using nylon bags. The 500 Yen bag has
2,000 pieces in it, weighing 14 kg each bag !

Fig 31 : The money bag up close

Fig 32 : The have the full bags on display so you can try to carry them,
of course they are all chained up so that you can't take it away! 

Fig 33 ; Just like the US Mint, they use Schuler coin press as well, these machines are
made in Germany that can press 750 coins per minute or 12.5 coins per second, assuming
it is in single die configuration. There are those with 4 die configuration that
produces 4 coins for every press, if so the speed will be 3 press every second.

Fig 34 : Gold and silver bullion on display with today's prices.

Fig 35 : Yes I get to touch the gold bar but you are not allowed to lift it! 

Fig 36 : Exonumia section

Fig 37 : Tokyo Summer Olympics medals - beautiful pieces! 

Fig 38 : Tokyo Summer Olympics medals - reverse

Fig 38 : Nagano Winter Olympic medals - 3D metal art!

Fig 39: You can find these at the roof top corners of the Osaka Castle

Fig 40 : Medals

Fig 41 : Medals

Fig 42 : Badges

Fig 43 : Badges

Fig 44 : History of Money Part 1 

Fig 45 : History of Money Part 2

Fig 46 : Chinese coinages 

Fig 47 : Chinese coinages Part 1 

Fig 48 : Chinese coinages Part 2 

Fig 49 : The famous Ōban (大判) coinage of Japan, minted from 1600-1659 under the Tokugawa shoganate 

Fig 50 : The Ōban (大判) making process

Fig 51 : The Ōban (大判)  - making the gold sheets

Fig 52 : The Ōban (大判) making process - pressing and stamping

Fig 53 : The Ōban (大判) making process

Fig 54 : Old paper money of Japan - circa 1800s

Fig 55 : Modern Japanese coinage - by year and denomination, a complete collection  

Fig 56 : World coin exhibits hall

Fig 57 : World coin exhibits hall

Fig 58: Commemorative silver coins of Japan

Fig 59: Flower series coins of Japan

Fig 60: Commemorative coins of Japan

Fig 61 : Awards won by the Japan Mint for coin designs

Fig 62 : The award winning gold phoenix coin

Fig 62 : Gold phoenix coin up close

Fig 63 : The mint library

Fig 64 : The mint library, love the view of the autumn leaves

Fig 65 : Outdoor exhibits - the retired coin press machines from 1835 - most likely steam powered press

Fig 66 : The front of the coin press

Fig 67 : The coin press with a huge steam powered piston with the small hole for the blank to be fed into
Fig 68 : The Mint Shop, small but interesting.

Fig 69 : Solid silver medallion 45mm, gold plated art, beautiful piece, beautiful price ! 

Hope you have learned something about coin minting process today. If you plan to visit Osaka Japan, do drop by at the mint museum.  Happy Collecting !


  1. Can we also buy commemoratives coins from the Mint?

  2. Yes you can! There is a mint shop to your left at the main entrance. :-)