An air conditioner is provided which is capable of simplifying conditions required for judging whether or not the amount of refrigerant is adequate. A refrigerant circuit (10) performs a cooling operation in which an outdoor heat exchanger (23) functions as a condenser of the refrigerant compressed in a compressor (21) and an indoor heat exchanger (42, 52) functions as an evaporator of the refrigerant condensed in the outdoor heat exchanger (23). Further, an outdoor expansion valve (38) is disposed at a position that is at once downstream of the outdoor heat exchanger (23) and upstream of a liquid refrigerant communication pipe (6) in the refrigerant flow direction in the refrigerant circuit (10) in the cooling operation, and shuts off the refrigerant flow. A refrigerant detection unit (39) is disposed upstream of the outdoor expansion valve (38) and detects the amount or the amount-related value of refrigerant accumulated upstream of the outdoor expansion valve (38).