The Katase River(片瀬川,Katase-gawa?) is a segment of a river in Shonan, central Japan, about 50 kilometers southwest of Tokyo.
The Katase is an approximately 3-kilometer-long segment of the river from Kawana (川名), Fujisawa, where the Sakai River (境川) and Kashio River join, to a point at Enoshima Island, where the river flows into Sagami Bay. The river's name refers to the Katase hills (片瀬山) along which the river flows.
As the Katase River and its tributaries are prone to flooding (especially in spring and during the typhoon season), as a protection they were encased in concrete during the postwar period. The rivers continue to flood, but do not overflow their banks as frequently as in the past.