To improve a fuel consumption by performing stratified charge, and manufacture an injection nozzle with an inexpensive and suitable material.

This rotary piston internal combustion engine comprises a casing 2 having an inner peripheral surface 6 and a rotary piston 4. The rotary piston 4 limits a plurality of chambers 8, 10, and 12 between the rotary piston 4 itself and the inner peripheral surface. The internal combustion engine comprises an air inflow passage 20, an exhaust passage 22, and a fuel injection device 24, and the fuel injection device comprises an injection nozzle 28 stored in the peripheral wall 26 of the air inflow passage. The injection flow from the injection nozzle is substantially directed toward the flow of intake air so as not to come into contact with the peripheral wall of the air inflow passage, and also directly directed toward the chamber 8 connected to the air inflow passage in the intake phase of combustion air.