1. A stator of an electric motor comprising:
a stator core which supports said coil, and
covers which are attached to said stator core so as to surround coil ends of said coil which stick out from end faces of the
stator core in the axial direction, wherein
said covers have outside diameters which are at least partially smaller than an outside diameter of said stator core,
said covers have coefficients of linear expansion which are larger than a coefficient of linear expansion of said stator core,
said covers expand by heat whereby said covers are made to closely contact a housing to be arranged around said stator.