The No.251 class auxiliary submarine chaser (第二百五十一号型駆潜特務艇,, Dai 251 Gō-gata Kusen-Tokumutei)[1] was a class of submarine chasers of the Imperial Japanese Navy (IJN), serving during World War II.

3 vessels were built in 1936 – 1939 under the Maru 2 Programme.

They have two subclasses, this article handles them collectively.