An aircraft propulsion system capable of improving the restartability of an engine is provided. An aircraft propulsion system includes: a plurality of engines (60-1 and 60-2); an electric generator connected to engine shafts (63-1 and 63-2); a plurality of electric motors; a plurality of rotors; and a controller (100) which controls an operation state of the plurality of engines (60-1 and 60-2). The controller (100) causes a part of the plurality of engines (60-1 and 60-2) to operate while stopping the remaining engine when a flight state is in a first state. The plurality of engines (60-1 and 60-2) include circulators (65-1 and 65-2). A plurality of communication pipes (68 and 69) which communicate the circulator (65-1) in the first engine (60-1) among the plurality of engines (60-1 and 60-2) with the circulator (65-2) in the second engine (60-2) are provided.