Disclosed is a stator core including a core back fixedly inserted onto an outer surface of a stationary member, a plurality of teeth protruding from the core back in an outer diameter direction, wherein a coil is wound around the plurality of teeth so as to allow magnetic flux from a magnet to flow to the teeth, front end portions defining outer edges of the teeth, respectively, and body portions defining a length of the teeth and having a width increasing from the core back toward the front end portions, respectively.