A uniflow scavenging 2-cycle engine that includes: a plurality of injection valves (160) provided at a fuel supply path (170) in parallel to each other and control ejection of fuel gas from injection ports (132e); a hydraulic pump (174) configured to discharge hydraulic oil and thereby switches the injection valves; a main flow path (176) configured to guide the hydraulic oil discharged from the hydraulic pump; a plurality of branch flow paths (178) which branch off from the main flow path and configured to guide the hydraulic oil from the main flow path to the injection valves; and switching valves (180) provided at the plurality of respective branch flow paths and configured to switch the injection valves. The branch flow paths are connected to one or more of the injection valves that control the ejection of the fuel gas from the plurality of injection ports adjacent to each other in a circumferential direction of a cylinder. The ejection of the fuel gas from the plurality of injection ports adjacent to each other is controlled by switching one switching valve provided at one of the branch flow paths.