[Problem] To provide a chiller type air conditioner that can perform a humidifying operation in one cooling cycle without increasing a facility cost. [Solution] An air conditioner includes: an air conditioning refrigerant circuit 5 performing a cooling operation and a heating operation by switching the cooling operation and the heating operation; and an air conditioning heat transfer medium circulation circuit 8 conditioning air of a cooled space 60, wherein connection switching means 34a and 34b for switching the connection of a first air conditioning user-side heat exchanger 28a and a second air conditioning user-side heat exchanger 28b to serial connection and parallel connection are installed in the air conditioning refrigerant circuit and a second air conditioning expansion valve is installed at a position between the first air conditioning user-side heat exchanger and the second air conditioning user-side heat exchanger. The air conditioning heat transfer medium circulation circuit 8 includes a first air conditioning heat transfer medium circuit 8a formed in a loop by connecting the first air conditioning user-side heat exchanger and a first indoor heat exchanger 61a through a pipe and a second air conditioning heat transfer medium circuit 8b formed in a loop by connecting the second air conditioning user-side heat exchanger and a second indoor heat exchanger 61b through a pipe.