To provide an outdoor unit for an air conditioner capable of preventing enlargement of a height of the outdoor unit caused by arrangement of a heat pipe heating condensed water on a drain path.

In the outdoor unit, the heat pipe 4 heating the condensed water on a drain pan 6 guiding the condensed water condensed by a heat exchanger 1 comprised by attaching a plurality of refrigerant tube arrangements 15 in piercing states through a plurality of heat transfer plates 11, to a drain opening, is attached in a piercing state to lower end part 11a neighborhoods of the heat transfer plates 11. By this, a vertical difference between a heating part 41 and a heat dissipation part 42 necessary for the heat pipe 4 using natural circulation of two layers of gas and liquid as a principle of operation, is absorbed within the height of the heat exchanger 1.