An oil separator capable of preventing breakage in a float with an extremely simple configuration is provided. An oil separator is to separate oil in a refrigerant that is discharged from a compressor and return the oil to the compressor. The oil separator includes: a tank, into which a refrigerant discharged from the compressor flows; a float having a hollow therein that is held vertically movably in the tank, the float moving up and down with a change of an oil level in the tank; and a needle valve to return oil in the tank to the compressor in accordance with up/down movement of the float. The float includes an equalizing tube having a lower end that opens at a bottom part in the float and an upper end that opens outside of the float and above the oil level in the tank.