The Cruiser submarine Type-B (巡潜乙型潜水艦, Junsen Otsu-gata sensuikan) was a class of submarine in the Imperial Japanese Navy (IJN) which served during World War II.

The Type-B submarines were similar to the Type-A apart from not having the headquarters installation.

The Type-B submarines were divided into four classes: Project number S37.

Eighteen boats were cancelled in late 1943, because the IJN was setting the Type E submarine [ja] (戊型潜水艦, Bo-gata sensuikan) as 1945's main submarines.

However, all boats were cancelled in late 1943, because the IJN concentrated on production of Type-E submarine (戊型潜水艦, Bo-gata sensuikan) from 1945.