PURPOSE:To provide a motor having a ventilation path for cooling in the stator made of a laminate of a plurality of electromagnetic steel plates in which the efficiency of cooling structure is enhanced by reducing heat to be radiated to the outside. CONSTITUTION:Vent parts 51-54 for ventilation path are made at four corners on the outside of an electromagnetic steel plate 21. Three ribs 51a are formed, for example, at the vent part 51 and total five vents 51b are made between these ribs 51a and a bolt hole 55a. Width delta1 of the rib 51a is designed at 2.5 mm or thereabout which is narrower than the conventional width of 3.5 mm or thereabout. Vents 51b1, 51b2 are made at the opposite ends of the vent 51b while extending thin toward the outside. Similarly, other vent parts 52-52 are provided with three ribs 52a-54a and five vents 52b-54b of identical shape, respectively.