A single-stage compressor including one compressing unit, includes: a housing having a compressing chamber formed therein and including a suction port, which is located in one side of the compressing chamber and into which a working fluid enters, and an injection port, which is located on the compressing chamber to be spaced apart from the suction port by a predetermined distance and into which an intermediate-pressure working fluid is injected; and an intermediate-pressure valve installed on an intermediate-pressure fluid flow path on which the intermediate-pressure working fluid moves and configured to control supply of the intermediate-pressure working fluid so that the intermediate-pressure working fluid is supplied to the injection port in response to an intermediate pressure of the compressing chamber. In the injection-type compressor having a single chamber, a working fluid is injected at an intermediate pressure (not in the proximity of a suction pressure) so that efficiency and capability of the injection-type compressor having a single chamber can be improved. The injection-type compressor having a single chamber has a simple structure and is easily manufactured so that a pressure of an injection port and a corresponding intermediate pressure can be selectively set in various ways.