To provide an air conditioner that can change the number of paths of an outdoor heat exchanger for achieving efficient operation in cooling and heating operations.

Pressure-reducing equipment 4 is connected to first, third, and fifth refrigerant channels 3a, 3c, and 3e of an outdoor heat exchanger 3 in parallel via first, second, and third on/off valves 6, 7, and 8, respectively, a junction (a) for the outlet side of the first, third, and fifth refrigerant channels 3a, 3c, and 3e is connected to the pressure-reducing equipment 4 via a fourth on/off valve 9, a fifth on/off valve 10 is connected between a four-way valve 2 and the junction (a) of the outlet side, the first, second, third, and fifth on/off valves 6, 7, 8, and 10 are closed in cooling operation, the fourth on/off valve 9 is opened for setting the refrigerant channel to three paths, the first, second, third, and fifth on/off valves 6, 7, 8, and 10 are opened in heating operation, and the fourth on/off valve 9 is closed for setting the refrigerant channel 6 to six paths.