An air-cooled motor having cooling-air passages each formed by a plurality of small ventilation passages extending through a front housing, a stator, and a rear housing, constructed in one piece. Cuttings are prevented from being accumulated at inlets of cooling-air passages. For example, the cooling-air passages are formed of ten small ventilation passages, each defined between adjacent ones of eleven ribs each forming part of the stator. All the eleven ribs are provided with respective front housing ribs. End faces of the front housing ribs on the cooling-air inlet side are uniform in height, and positioned in an identical plane. Cooling air flows into the small ventilation passages in the direction of an arrow. In this case, the end faces of the small ventilation passages on the cooling-air inlet side are aligned, so that cuttings contained in cooling air are accumulated only on the end faces of ribs defining the small ventilation passages on the cooling-air inlet side, forming accumulation layers thereon, which prevents the small ventilation passages from being clogged with accumulations of cuttings.