A uniflow scavenging type two-cycle engine in which exhaust gas in a cylinder is pushed out of an exhaust port by scavenging air flowed in from a scavenging port, the uniflow scavenging type two-cycle engine comprising: a valve body which openably closes the exhaust port; an injector which is provided on a facing surface of the valve body facing a piston disposed inside the cylinder, and injects air; a shaft fixed to a side of the valve body far from the facing surface; a drive unit which applies a load to the shaft to move the valve body to an open position at which the valve body opens the exhaust port; a gas spring mechanism including a gas chamber in which air is stored, in which at least part of the shaft is positioned, and a volume of which is reduced when the valve body moves to the open position; and a communication passage which is formed in the valve body and the shaft and allows the gas chamber and the injector to communicate with each other, wherein the communication passage is provided with a check valve which allows a flow of air from the gas chamber to the injector and restricts a flow of air from the injector to the gas chamber, the communication passage is provided with a large inner diameter portion opening at the facing surface, and a small inner diameter portion having a smaller inner diameter than that of the large inner diameter portion, a tapered surface is formed at a connection portion between the large inner diameter portion and the small inner diameter portion, the inner diameter of the tapered surface gradually decreases from the large inner diameter portion toward the small inner diameter portion, and the tapered surface functions as a valve seat of the check valve, the injector includes a nozzle unit and a plug unit, a main body of the nozzle unit is formed in a hemispherical shape, a flat surface portion of the main body contacts the facing surface, and a curved surface portion of the main body faces the piston, in the nozzle unit, a hollow portion recessed toward the curved surface portion is formed at the flat surface portion, and a plurality of radiation holes penetrating from the hollow portion to the curved surface portion are radially provided, the plug unit is a cylindrical member having a plug hole penetrating in a stroke direction of the piston and is engaged with the large inner diameter portion, one end of the plug unit is fixed to the flat surface portion of the nozzle unit, and the hollow portion and the radiation holes of the injector communicate with the communication passage through the plug hole of the plug unit, and a coil spring that pushes the check valve toward the tapered surface is accommodated in the large inner diameter portion and contacts the other end of the plug unit. a valve body which openably closes the exhaust port; an injector which is provided on a facing surface of the valve body facing a piston disposed inside the cylinder, and injects air; a shaft fixed to a side of the valve body far from the facing surface; a drive unit which applies a load to the shaft to move the valve body to an open position at which the valve body opens the exhaust port; a gas spring mechanism including a gas chamber in which air is stored, in which at least part of the shaft is positioned, and a volume of which is reduced when the valve body moves to the open position; and a communication passage which is formed in the valve body and the shaft and allows the gas chamber and the injector to communicate with each other, wherein the communication passage is provided with a check valve which allows a flow of air from the gas chamber to the injector and restricts a flow of air from the injector to the gas chamber, the communication passage is provided with a large inner diameter portion opening at the facing surface, and a small inner diameter portion having a smaller inner diameter than that of the large inner diameter portion, a tapered surface is formed at a connection portion between the large inner diameter portion and the small inner diameter portion, the inner diameter of the tapered surface gradually decreases from the large inner diameter portion toward the small inner diameter portion, and the tapered surface functions as a valve seat of the check valve, the injector includes a nozzle unit and a plug unit, a main body of the nozzle unit is formed in a hemispherical shape, a flat surface portion of the main body contacts the facing surface, and a curved surface portion of the main body faces the piston, in the nozzle unit, a hollow portion recessed toward the curved surface portion is formed at the flat surface portion, and a plurality of radiation holes penetrating from the hollow portion to the curved surface portion are radially provided, the plug unit is a cylindrical member having a plug hole penetrating in a stroke direction of the piston and is engaged with the large inner diameter portion, one end of the plug unit is fixed to the flat surface portion of the nozzle unit, and the hollow portion and the radiation holes of the injector communicate with the communication passage through the plug hole of the plug unit, and a coil spring that pushes the check valve toward the tapered surface is accommodated in the large inner diameter portion and contacts the other end of the plug unit.