An air conditioning apparatus comprising: an outdoor unit which comprises a compressor and an outdoor heat exchanger and through which a refrigerant is circulated; an indoor unit through which water is circulated; a heat exchanger (101, 102) in which the refrigerant and the water are heat-exchanged with each other; a high-pressure guide tube (121, 122) extending from a high-pressure gas tube of the outdoor unit so as to be connected to one side of the heat exchanger; a high-pressure valve (123, 124) installed in the high-pressure guide tube (121, 122), the high-pressure valve (123, 124) being configured to be opened and closed; a low-pressure guide tube (125, 126) extending from a low-pressure gas tube of the outdoor unit so as to be combined with the high-pressure guide tube (121, 122); a low-pressure valve (127, 128) installed in the low-pressure guide tube (125, 126), the low-pressure valve (127, 128) being configured to be opened and closed; a refrigerant tube (110, 115) having one end defining a refrigerant branch point (112, 117), at which the high-pressure guide tube (121, 122) and the low-pressure guide tube (125, 126) are combined with each other, and the other end connected to a refrigerant passage of the heat exchanger; a liquid guide tube (141, 142) extending from a liquid tube of the outdoor unit so as to be connected to the other side of the heat exchanger; a flow valve (143, 144) installed in the liquid guide tube (141, 142) to control a flow rate of the refrigerant; a bypass tube (200, 210, 220) configured to connect a bypass branch point (112, 117) of the high-pressure gas tube to a bypass combination point of the liquid guide tube (141, 142) to bypass a high-pressure refrigerant existing in the high-pressure guide tube (121, 122) to the liquid guide tube (141, 142); a bypass valve (215, 225) installed in the bypass tube (200, 210, 220); and a controller controls operations of the high-pressure valve (123, 124), the low-pressure valve (127, 128), the flow valve (143, 144), and the bypass valve (215, 225). an outdoor unit which comprises a compressor and an outdoor heat exchanger and through which a refrigerant is circulated; an indoor unit through which water is circulated; a heat exchanger (101, 102) in which the refrigerant and the water are heat-exchanged with each other; a high-pressure guide tube (121, 122) extending from a high-pressure gas tube of the outdoor unit so as to be connected to one side of the heat exchanger; a high-pressure valve (123, 124) installed in the high-pressure guide tube (121, 122), the high-pressure valve (123, 124) being configured to be opened and closed; a low-pressure guide tube (125, 126) extending from a low-pressure gas tube of the outdoor unit so as to be combined with the high-pressure guide tube (121, 122); a low-pressure valve (127, 128) installed in the low-pressure guide tube (125, 126), the low-pressure valve (127, 128) being configured to be opened and closed; a refrigerant tube (110, 115) having one end defining a refrigerant branch point (112, 117), at which the high-pressure guide tube (121, 122) and the low-pressure guide tube (125, 126) are combined with each other, and the other end connected to a refrigerant passage of the heat exchanger; a liquid guide tube (141, 142) extending from a liquid tube of the outdoor unit so as to be connected to the other side of the heat exchanger; a flow valve (143, 144) installed in the liquid guide tube (141, 142) to control a flow rate of the refrigerant; a bypass tube (200, 210, 220) configured to connect a bypass branch point (112, 117) of the high-pressure gas tube to a bypass combination point of the liquid guide tube (141, 142) to bypass a high-pressure refrigerant existing in the high-pressure guide tube (121, 122) to the liquid guide tube (141, 142); a bypass valve (215, 225) installed in the bypass tube (200, 210, 220); and a controller controls operations of the high-pressure valve (123, 124), the low-pressure valve (127, 128), the flow valve (143, 144), and the bypass valve (215, 225).