An outdoor unit for an air-conditioning apparatus includes at least a heat exchanger, a fan, a compressor, and a box-like casing housing these components and having an air inlet and an air outlet. The compressor is arranged at a location other than an air passage in which air having flowed in through the air inlet flows through the heat exchanger and the fan to the air outlet. The heat exchanger includes a plurality of heat exchange portions, and these heat exchange portions are arranged in a zigzag shape.