The compressor is provided with an oil separator for separating oil from refrigerant gas introduced into a separation chamber, an annular space for reserving oil separated from the refrigerant gas, and a reservoir chamber for reserving the thus separated oil. The oil separator is provided in a cylindrical hole formed in a discharge chamber from which the refrigerant gas is discharged and a lid for partitioning the cylindrical hole from the discharge chamber is provided in the cylindrical hole. The oil separator introduces the refrigerant gas from the discharge chamber to the separation chamber via the introduction passage. The annular space is provided around the lid and connected to the reservoir chamber via an oil passage. The reservoir chamber is connected to a crank chamber of a pressure lower than that in the discharge chamber.