The No.1-class patrol boat (第一号型哨戒特務艇,, Dai Ichi Gō-gata Shōkai-Tokumutei) was a class of auxiliary patrol boat (picket boat) of the Imperial Japanese Navy (IJN), serving during World War II.

280 vessels were planned under the Maru Sen Programme (Ship # 2121–2400), however, only 27 vessels were completed before the end of the war.