A compressor has a high-pressure relief valve and a low-pressure relief valve. The high-pressure relief valve in use for a discharge region opens when the pressure of gas in the discharge region is more than a first predetermined pressure. The high-pressure relief valve is provided with a first shim. The low-pressure relief valve in use for a suction region opens when the pressure of gas in the suction region is more than a second predetermined pressure which is lower than the first predetermined pressure. The low-pressure relief valve is provided with a second shim. The high-pressure relief valve and the low-pressure relief valve have similar structure to each other.