To provide a marine electric propulsion system suffering from less power loss in a power converter, such as an inverter, and capable of effectively using stored electric power even when electricity storage devices have dispersion in capacity.

Stator windings of a motor for propulsion 17 for driving a propulsion propeller 8 is divided into a plurality of groups of windings 17A, 17B. Power supply devices 18A, 18B composed of electricity storage devices 19A, 19B, first inverters 5A, 5B and second inverters 14A, 14B are prepared in a number corresponding to a number of stator windings 17A, 17B. The motor for propulsion 17 is driven respectively by the first inverters 5A and 5B in the respective power supply devices 18A, 18B, and an inboard load is operated respectively by the second inverters 14A and 14B.