A compressor incorporated with an oil separator having a separation chamber, which is placed adjacent to a discharge chamber, has a space formed in the entire inside of the separation chamber, separates oil-containing gas, being introduced, into gas and oil by centrifugal separation, allows the separated oil to drop downward, and upwardly extracts the separated gas, and also having a lower hole for introducing the separated oil into an oil storing chamber. The oil separator is formed as a joining structure of two compressor forming members, and a portion of the oil storing chamber, other than a portion where the lower hole is opened, is communicated with the separation chamber via a gas release passageway at least a part of which is formed between the two compressor forming members. Gas is efficiently discharged from the portion of the oil storing chamber where the lower hole of the oil separator is not opened, a sufficient amount of stored oil is secured in the oil storing chamber, and in addition, workability in production of the device is improved.