Disclosed is a gas compressor capable of preventing deformation of a filter used for separating oil contained in a compressed gas. The gas compressor includes a suction port, a suction chamber, a gas compressing portion, a compressed gas releasing portion provided in the gas compressing portion, a discharge chamber, and a discharge port. Provided in the discharge chamber is a filter for separating oil contained in the compressed gas. The filter is configured such that the outer peripheral portion of the filter is expanded peripherally upon its deformation caused when the force (dynamic pressure) of a jet stream formed by the flow of the compressed gas released from the compressed gas releasing portion and the force (static pressure) due to a difference in pressure between front and rear sides of the filter which is generated by the flow path resistance in the filter are applied to the filter whereby the force with which the filter is held in close contact with the filter installation portion is increased.