This gas-liquid separator is provided with: a tank part which stores and separates a refrigerant; and a pipe connection part forming outlet/inlet ports for the refrigerant from the tank part. The pipe connection part has: a first connection part having a first connection pipe which guides the refrigerant to an expansion valve; a second connection part having a second connection pipe through which the cooled refrigerant returns; a third connection part having a third connection pipe which guides the refrigerant to a compressor; a fourth connection part having a fourth connection pipe which guides the refrigerant into the tank part from an outdoor heat exchanger; and a first flow path switching valve which allows the inside of the tank part to communicate with the third connection pipe during heating operations, and allows the second connection pipe to communicate with the third connection pipe during cooling operations.