An air-conditioning hot-water supply complex system comprising: an air-conditioning refrigeration cycle that has a first refrigerant circuit, in which an air-conditioning compressor, a flow channel switching means, an outdoor heat exchanger, an indoor heat exchanger, and air-conditioning throttle means are connected in series, and a refrigerant-refrigerant heat exchanger and hot-water supply heat source throttle means that are connected each other in series are connected to said indoor heat exchanger and said air-conditioning throttle means in parallel, and that makes an air-conditioning refrigerant be circulated in said first refrigerant circuit; a hot-water supply refrigeration cycle that has a second refrigerant circuit, in which a hot-water supply compressor, a heat medium-refrigerant heat exchanger, hot-water supply throttle means and said refrigerant-refrigerant heat exchanger that are connected in series, and that makes a hot-water supply refrigerant be circulated in said second refrigerant circuit; wherein said air-conditioning refrigeration cycle and said hot-water supply refrigeration cycle are cascade-connected so as to perform heat exchange between said air-conditioning refrigerant and said hot-water supply refrigerant in said refrigerant-refrigerant heat exchanger, characterized in that a hot-water supply load (3, 3a, 3b) that has a water circuit, in which a water circulation pump, said heat medium-refrigerant heat exchanger, and a hot water storage tank are connected in series, and that makes water for hot-water supply be circulated in said water circuit, wherein said hot-water supply refrigeration cycle and said hot-water supply load (3, 3a, 3b) are cascade-connected so as to perform heat exchange between said hot-water supply refrigerant and said water in said heat medium-refrigerant heat exchanger, and wherein in said water circuit, a bypass pipe is provided which connects between said heat medium-refrigerant heat exchanger and said hot water storage tank, and between said hot water storage tank and said water circulation pump and a volume of the heat medium circulating in said water circuit in the portion other than said heat medium-refrigerant heat exchanger is substantially equal to a volume of the heat medium circulating in said water circuit in said heat medium-refrigerant heat exchanger, and the water circuit is configured to, when said hot-water supply compressor starts up, transmit the heat medium to said bypass pipe to increase the temperature of the volume of the heat medium which is equivalent to a volume of water held in said heat medium-refrigerant heat exchanger, and then to circulate the heat medium in said water circuit. an air-conditioning refrigeration cycle that has a first refrigerant circuit, in which an air-conditioning compressor, a flow channel switching means, an outdoor heat exchanger, an indoor heat exchanger, and air-conditioning throttle means are connected in series, and a refrigerant-refrigerant heat exchanger and hot-water supply heat source throttle means that are connected each other in series are connected to said indoor heat exchanger and said air-conditioning throttle means in parallel, and that makes an air-conditioning refrigerant be circulated in said first refrigerant circuit; a hot-water supply refrigeration cycle that has a second refrigerant circuit, in which a hot-water supply compressor, a heat medium-refrigerant heat exchanger, hot-water supply throttle means and said refrigerant-refrigerant heat exchanger that are connected in series, and that makes a hot-water supply refrigerant be circulated in said second refrigerant circuit; wherein said air-conditioning refrigeration cycle and said hot-water supply refrigeration cycle are cascade-connected so as to perform heat exchange between said air-conditioning refrigerant and said hot-water supply refrigerant in said refrigerant-refrigerant heat exchanger, characterized in that a hot-water supply load (3, 3a, 3b) that has a water circuit, in which a water circulation pump, said heat medium-refrigerant heat exchanger, and a hot water storage tank are connected in series, and that makes water for hot-water supply be circulated in said water circuit, wherein said hot-water supply refrigeration cycle and said hot-water supply load (3, 3a, 3b) are cascade-connected so as to perform heat exchange between said hot-water supply refrigerant and said water in said heat medium-refrigerant heat exchanger, and wherein in said water circuit, a bypass pipe is provided which connects between said heat medium-refrigerant heat exchanger and said hot water storage tank, and between said hot water storage tank and said water circulation pump and a volume of the heat medium circulating in said water circuit in the portion other than said heat medium-refrigerant heat exchanger is substantially equal to a volume of the heat medium circulating in said water circuit in said heat medium-refrigerant heat exchanger, and the water circuit is configured to, when said hot-water supply compressor starts up, transmit the heat medium to said bypass pipe to increase the temperature of the volume of the heat medium which is equivalent to a volume of water held in said heat medium-refrigerant heat exchanger, and then to circulate the heat medium in said water circuit.