An air conditioning apparatus and a refrigerant quantity determination method are provided, whereby a refrigerant quantity can be determined in a simple and accurate manner without compromising the reliability of a compressor. A refrigerant circuit (10) has a compressor (21), an outdoor heat exchanger (23) that functions as a condenser, an indoor expansion valve (41, 51), an indoor heat exchanger (42, 52) that functions as an evaporator, an indoor unit interconnection pipe (4b, 5b), a liquid refrigerant connection pipe (6), a gas refrigerant connection pipe (7), and an outdoor unit interconnection pipe (8). A controller (9) performs liquefaction control for liquefying refrigerant and placing the refrigerant in a portion extending from the indoor expansion valve (41, 51) to the outdoor heat exchanger (23). The controller (9) directly or indirectly regulates the flow rate of refrigerant flowing through a liquid bypass circuit (70) from a liquid reserving portion (Q) toward the gas refrigerant connection pipe (7). A liquid level detection sensor (39) detects at least one of either a volume of liquid refrigerant in the portion where liquid refrigerant accumulates and a physical quantity equivalent to the volume.