To provide a 10-pole/9-slot synchronous motor including nine teeth 2b that are divided into three phases, each having three adjacent teeth. A stator iron core 2 is configured such that a value obtained by dividing b by a is larger than 0.5 where the a is a width of a teeth tip 2c, which is provided on an inner diameter side of a tooth of the teeth 2b formed on the stator iron core 2, from a base portion 2b1 between the teeth tip 2c and the tooth 2b to a circumferential end 2c1 of the teeth tip 2c and the b is a thickness of the teeth tip 2c from the base portion 2b1 to an inner-diameter side surface 2c2 of the teeth tip 2c.