The heat exchanger includes heat exchange units. Each of the heat exchange units includes a plurality of plate fins and a plurality of flat tubes. The plate fins are arranged spaced apart from one another at intervals so as to allow air to flow therebetween. The flat tubes each have an L shape by bending and inserted through the plate fins so that a refrigerant flows therethrough in a direction in which the plate fins are arranged. The heat exchange units are combined to each other so as to form a rectangular shape. Thus, heat exchange can be efficiently performed by increasing the mounting area.