An air conditioning device for a vehicle has a compressor that supplies a high-pressure refrigerant by drawing and discharging a refrigerant, an air heating heat exchanger heating air that is to be blown into a vehicle cabin by using heat of the high-pressure refrigerant, a pressure reduction part expanding and decompressing the high-pressure refrigerant and supplying as an intermediate-pressure refrigerant and a low-pressure refrigerant, a first low-pressure side heat exchanger exchanging heat between the intermediate-pressure refrigerant and a heating medium other than the air, a second low-pressure side heat exchanger cooling the heating medium by exchanging heat between the low-pressure refrigerant and the heating medium, a first heating medium circuit through which the heating medium cooled in the second low-pressure side heat exchanger circulates, and a heating medium-air heat exchanger causing the heating medium to absorb heat by exchanging heat between the air and the heating medium circulating through the first heating medium circuit. The heating medium heated in the high-pressure side heat exchanger is capable of being introduced to the first low-pressure side heat exchanger.