The Ro-100-class submarine (呂百型潜水艦, Ro-hyaku-gata Sensuikan) was a group of medium-sized coastal submarines built for the Imperial Japanese Navy (IJN) during World War II.

They had a double hull and a diving depth of 75 meters (246 ft).

[2] For surface running, the boats were powered by two 500-brake-horsepower (373 kW) diesel engines, each driving one propeller shaft.

When submerged each propeller was driven by a 380-horsepower (283 kW) electric motor.

On the surface, the Ro-100s had a range of 3,500 nautical miles (6,500 km; 4,000 mi) at 12 knots (22 km/h; 14 mph); submerged, they had a range of 60 nmi (110 km; 69 mi) at 3 knots (5.6 km/h; 3.5 mph).