To reduce noise of a motor 10 by suppressing unevenness of tightening force P due to temperature distribution inside the motor 10 when the motor 10 is driven.

The motor 10 includes: a stator core 22 structured with a plurality of split cores 26; a cylindrical body 24, which tightens and fixes the stator core 22; and a case 16, which accommodates and fixes the cylindrical body 24. When a linear expansion coefficient of the cylindrical body 24 is large exceeding that of the stator core 22, the stator core 22 is fixed to the cylindrical body 24 so as to cause the tightening force P to increase gradually as it leaves from fixed areas M in the direction of an axis 38.