Today, the Omizuya is found in most of the shrine in Japan. Visitors purify their hands and mouths before worship. However, worshippers used to wash their hands and mouths in the natural river and the spring. The Omizuya of Toshogu Shrine was built for the first time as the place of purification for visitors.

It is 1.2m wide, is 2.6m deep, and is 1m high. Also, feudal clan of Nabeshima dedicated the granite-made basin in 1618. The law of siphon sends water from the hole of 15cm.

There are sculptures of flying dragon and wave under the roof. The flying dragon has wings, and it is treated as the spiritual beast, which controls the water.

West corner of the roof has been cut, but it is for an amulet. Also, it is told that the West corner is cut not to disturb growth of cedar.