A two-stroke engine (1) includes a cylinder (2) having a scavenging port (23) and an exhaust port (24), a piston (3) provided in the cylinder (2), a first ejection part (61) for ejecting liquid ammonia into a combustion chamber (20), and a supercharger (5) for pressurizing a suction gas to generate a scavenging gas. In the two-stroke engine (1), the first ejection part (61) ejects liquid ammonia into the combustion chamber (20) within a period of time from when supply of the scavenging gas through the scavenging port (23) into the combustion chamber (20) is started until when the piston (3) next reaches top dead center. It is thus possible to reduce the temperature of gas within the combustion chamber (20) by the heat of vaporization of the liquid ammonia, reduce the pressure in the combustion chamber (20) during compression, and reduce the amount of compression work.