An air conditioning apparatus comprising: a plurality of use-side heat exchangers (30a, 30b, 30c, 30d); a heating inter-heat-medium heat exchanger (14a, 14b) and a cooling inter-heat-medium heat exchanger (14a, 14b) that exchange heat between a heat medium circulated in a heat medium circulating circuit including at least one of the use-side heat exchangers and a heat source fluid fed from a heat source unit to respectively heat and cool the heat medium; a first heat medium feeding unit (31a, 31b) causing a heat medium to flow through a flow path connecting the heating inter-heat-medium heat exchanger and the use-side heat exchangers and a second heat medium feeding unit (31a, 31b) causing the heat medium to flow through a flow path connecting the cooling inter-heat-medium heat exchanger and the use-side heat exchangers; outside air temperature detecting means for detecting outside air temperature; and a controller that controls the flow path of the heat medium, the air conditioning apparatus capable for simultaneous operation of cooling and heating in which each of the use-side heat exchangers connects either the heating inter-heat-medium heat exchanger or the cooling inter-heat-medium heat exchanger and in which the heating inter-heat-medium heat exchanger and the cooling inter-heat-medium heat exchanger operate simultaneously, characterized in that the controller compares the outside air temperature detected by the outside air temperature detecting means with a predetermined temperature at a preset, preheats about half of the plurality of use-side heat exchangers (30a, 30b, 30c, 30d) by driving the heat medium feeding unit connected to the heat medium circulating circuit corresponding with about the half thereof to perform heat-up operation of the heat medium for about the half of the plurality of use-side heat exchangers (30a, 30b, 30c, 30d) when the outside air temperature is lower than the first predetermined temperature, and selects the use-side heat exchangers (30a, 30b, 30c, 30d) to be preheated out of all the use-side heat exchangers in descending order of length of a heat medium pipe between each of the use-side heat exchangers (30a, 30b, 30c, 30d) and a unit including the heating inter-heat-medium heat exchanger (14a, 14b). a plurality of use-side heat exchangers (30a, 30b, 30c, 30d); a heating inter-heat-medium heat exchanger (14a, 14b) and a cooling inter-heat-medium heat exchanger (14a, 14b) that exchange heat between a heat medium circulated in a heat medium circulating circuit including at least one of the use-side heat exchangers and a heat source fluid fed from a heat source unit to respectively heat and cool the heat medium; a first heat medium feeding unit (31a, 31b) causing a heat medium to flow through a flow path connecting the heating inter-heat-medium heat exchanger and the use-side heat exchangers and a second heat medium feeding unit (31a, 31b) causing the heat medium to flow through a flow path connecting the cooling inter-heat-medium heat exchanger and the use-side heat exchangers; outside air temperature detecting means for detecting outside air temperature; and a controller that controls the flow path of the heat medium, the air conditioning apparatus capable for simultaneous operation of cooling and heating in which each of the use-side heat exchangers connects either the heating inter-heat-medium heat exchanger or the cooling inter-heat-medium heat exchanger and in which the heating inter-heat-medium heat exchanger and the cooling inter-heat-medium heat exchanger operate simultaneously, characterized in that the controller compares the outside air temperature detected by the outside air temperature detecting means with a predetermined temperature at a preset, preheats about half of the plurality of use-side heat exchangers (30a, 30b, 30c, 30d) by driving the heat medium feeding unit connected to the heat medium circulating circuit corresponding with about the half thereof to perform heat-up operation of the heat medium for about the half of the plurality of use-side heat exchangers (30a, 30b, 30c, 30d) when the outside air temperature is lower than the first predetermined temperature, and selects the use-side heat exchangers (30a, 30b, 30c, 30d) to be preheated out of all the use-side heat exchangers in descending order of length of a heat medium pipe between each of the use-side heat exchangers (30a, 30b, 30c, 30d) and a unit including the heating inter-heat-medium heat exchanger (14a, 14b).