An injectable compressor comprising: a compressing portion forming a compression chamber, and compressing a sucked refrigerant sucked in by the compression chamber from a suction pressure to a discharge pressure, and a refrigerant injecting portion injecting an injection refrigerant into an intermediate pressure portion where the sucked refrigerant has an intermediate pressure, which is higher than the suction pressure and lower than the discharge pressure, in the compression chamber formed by the compressing portion, the refrigerant injecting portion comprising: a refrigerant inlet chamber in which the injection refrigerant flows from outside; and an on-off valve chamber connected to the refrigerant inlet chamber and the intermediate pressure portion of the compression chamber, formed with a connection port to the refrigerant inlet chamber and a connection port to the compression chamber, which are formed on a same surface in the on-off valve chamber, and including an on-off valve (30,32) opening and closing the connection port to the refrigerant inlet chamber based on a pressure difference between a refrigerant on a refrigerant inlet chamber side and a refrigerant on a compression chamber side; wherein the on-off valve (30,32) is placed movably along a predetermined moving direction in the on-off valve chamber, and is formed with a hole at a position overlapping with the connection port to the intermediate pressure portion when the connection port to the refrigerant inlet chamber is closed. a compressing portion forming a compression chamber, and compressing a sucked refrigerant sucked in by the compression chamber from a suction pressure to a discharge pressure, and a refrigerant injecting portion injecting an injection refrigerant into an intermediate pressure portion where the sucked refrigerant has an intermediate pressure, which is higher than the suction pressure and lower than the discharge pressure, in the compression chamber formed by the compressing portion, the refrigerant injecting portion comprising: a refrigerant inlet chamber in which the injection refrigerant flows from outside; and an on-off valve chamber connected to the refrigerant inlet chamber and the intermediate pressure portion of the compression chamber, formed with a connection port to the refrigerant inlet chamber and a connection port to the compression chamber, which are formed on a same surface in the on-off valve chamber, and including an on-off valve (30,32) opening and closing the connection port to the refrigerant inlet chamber based on a pressure difference between a refrigerant on a refrigerant inlet chamber side and a refrigerant on a compression chamber side; wherein the on-off valve (30,32) is placed movably along a predetermined moving direction in the on-off valve chamber, and is formed with a hole at a position overlapping with the connection port to the intermediate pressure portion when the connection port to the refrigerant inlet chamber is closed. a refrigerant inlet chamber in which the injection refrigerant flows from outside; and an on-off valve chamber connected to the refrigerant inlet chamber and the intermediate pressure portion of the compression chamber, formed with a connection port to the refrigerant inlet chamber and a connection port to the compression chamber, which are formed on a same surface in the on-off valve chamber, and including an on-off valve (30,32) opening and closing the connection port to the refrigerant inlet chamber based on a pressure difference between a refrigerant on a refrigerant inlet chamber side and a refrigerant on a compression chamber side; wherein the on-off valve (30,32) is placed movably along a predetermined moving direction in the on-off valve chamber, and is formed with a hole at a position overlapping with the connection port to the intermediate pressure portion when the connection port to the refrigerant inlet chamber is closed.