A pressure wheel is a machine used to manufacture black powder. In order to modernize gunpowder production, Tarozaemon Sawa, a retainer of the Tokugawa Shogunate, was ordered by the Tokugawa Shogunate to go to the Netherlands in 1865 to learn how to make gunpowder. Sawa purchased this pressure grinder from Belgium and brought it back to Japan. This monument is the actual one that was actually used to manufacture gunpowder using the water power of the Shakujii River, and was installed as a monument by the Ministry of the Army in 1922 after its use.