An air conditioner including an outdoor device that includes a bypass path connecting a discharge side of the compressor and a suction side of the compressor, an on-off valve configured to open/close the bypass path, and a control device configured to control the compressor, the decompression device, and the on-off valve. The control device opens the on-off valve in a state in which the compressor is stopped to execute such bypass opening that refrigerant circulates, through the bypass path, from the discharge side of the compressor in a refrigerant storage state in which refrigerant is stored to the suction side of the compressor in a substantially vacuum state, and evaluates a volume of the pipe.