An air conditioning apparatus comprising: an outdoor unit including a compressor and an outdoor heat exchanger and configured to circulate refrigerant; an indoor unit configured to circulate water; a first heat exchanger (140, 141) configured to perform heat exchange between the refrigerant and the water; wherein the indoor unit is fluidly connected to the first heat exchanger by inlet and discharge water pipes; a first valve device connected to the first heat exchanger and configured to control a flow direction of the refrigerant; a first connection pipe connected to a first port of the first valve device such that high-pressure refrigerant compressed in the compressor flows therethrough, and forming a first bypass branch part; a second connection pipe connected to a second port of the first valve device and connected to the first heat exchanger (140, 141); a third connection pipe connected to a third port of the first valve device such that evaporated low-pressure refrigerant flows therethrough, and forming a second bypass branch part; a fourth connection pipe connected to the first heat exchanger (140, 141) and provided with a first expansion valve; first, second and third outdoor-unit connection pipes (20, 25, 27) connected to the outdoor unit; a bypass pipe connecting the first bypass branch part of the first connection pipe with the second bypass branch part of the third connection pipe to allow bypassing of the high-pressure refrigerant in the first connection pipe to the third connection pipe; and a bypass valve mounted in the bypass pipe, wherein the first outdoor-unit connection pipe is connected to the first connection pipe, wherein the second outdoor-unit connection pipe is connected to the third connection pipe, and wherein the third outdoor-unit connection pipe is connected to the fourth connection pipe, wherein, during cooling operation of the indoor unit, refrigerant condensed in the outdoor unit is evaporated in the first heat exchanger (140, 141) through the fourth connection pipe, wherein, during cooling operation of the indoor unit, the bypass valve is configured to be opened to allow bypassing of high-pressure refrigerant of the first connection pipe to the third connection pipe; and an expansion device provided in the bypass pipe and located at a point between the second bypass branch part and the bypass valve to decompress the refrigerant. an outdoor unit including a compressor and an outdoor heat exchanger and configured to circulate refrigerant; an indoor unit configured to circulate water; a first heat exchanger (140, 141) configured to perform heat exchange between the refrigerant and the water; wherein the indoor unit is fluidly connected to the first heat exchanger by inlet and discharge water pipes; a first valve device connected to the first heat exchanger and configured to control a flow direction of the refrigerant; a first connection pipe connected to a first port of the first valve device such that high-pressure refrigerant compressed in the compressor flows therethrough, and forming a first bypass branch part; a second connection pipe connected to a second port of the first valve device and connected to the first heat exchanger (140, 141); a third connection pipe connected to a third port of the first valve device such that evaporated low-pressure refrigerant flows therethrough, and forming a second bypass branch part; a fourth connection pipe connected to the first heat exchanger (140, 141) and provided with a first expansion valve; first, second and third outdoor-unit connection pipes (20, 25, 27) connected to the outdoor unit; a bypass pipe connecting the first bypass branch part of the first connection pipe with the second bypass branch part of the third connection pipe to allow bypassing of the high-pressure refrigerant in the first connection pipe to the third connection pipe; and a bypass valve mounted in the bypass pipe, wherein the first outdoor-unit connection pipe is connected to the first connection pipe, wherein the second outdoor-unit connection pipe is connected to the third connection pipe, and wherein the third outdoor-unit connection pipe is connected to the fourth connection pipe, wherein, during cooling operation of the indoor unit, refrigerant condensed in the outdoor unit is evaporated in the first heat exchanger (140, 141) through the fourth connection pipe, wherein, during cooling operation of the indoor unit, the bypass valve is configured to be opened to allow bypassing of high-pressure refrigerant of the first connection pipe to the third connection pipe; and an expansion device provided in the bypass pipe and located at a point between the second bypass branch part and the bypass valve to decompress the refrigerant.