An air conditioner that includes a heat exchanger including: heat-transfer pipes extending in a horizontal direction and spaced apart at predetermined intervals in a vertical direction and configured to allow a thermal medium to flow therein. A part of the heat transfer pipes are used for at least one inflow path into which the thermal medium flows from the outside of the heat exchanger and the other part of the heat transfer pipes are used for at least one outflow path from which the thermal medium flows out to the outside. At least one connection pipe through which an outlet side of one of the at least one inflow path communicates with an inlet side of one of the at least one outflow path.