Tonosama Shouzu is a source of water that flows without cease at the threshold of Kasugaonsenkyo, in Toyama prefecture. It is chosen as the site of Toyama's best water and is also among the top 100 best sources of water in Japan.

It is said that the water is similar to that of Ana-no-tani-no-reisui in Kamiichi. Many people living in the neighborhood often go to the spring to collect water. It is comfortable to drink and soothes the throat.

The name Tonosama Shouzu derives from the legend that the lord of Toyama clan, who only drank its waters, never suffered ill-health.

Around the spring are recreation facilities, parks and forests. Kasugasou, Garaku and Oosawano Palace are in the vicinity, and the spring is a landmark of Toyama prefecture.