To provide a hull resistance reduction system and a hull resistance reduction method which are capable of compressing air that becomes bubbles by using the energy of exhaust gas and stably supplying bubbles to a hull external surface in the water.

A hull resistance reduction system comprises: a main engine 1; an exhaust turbine compressor 20 which operates by leading a part of exhaust gas from the main engine 1 to the compressor; and an ejection nozzle 24 for leading compressed air led from the exhaust turbine compressor 20 to a hull external surface of a ship in the water. The exhaust turbine compressor 20 includes: an exhaust turbine 20b which is rotationally driven by the led exhaust gas; a compressor 20a which obtains rotational driving force of the exhaust turbine 20b to compress air; an electric power generator 21 which performs power generation by the exhaust turbine 20b and assistance of the compressor 20a.