Patent ID: 7535144

Claim:
An electric tool, comprising: a rotor; a stator, in which the rotor is rotatably accommodated, comprising: a cylindrical yoke with a continuous circumference; and a cylindrical magnet with a continuous circumference, arranged so as to extend along an inner circumference of the yoke, and having a plurality of magnetic poles generating a magnetic field operable to rotate the rotor; and a tip tool, coupled to the rotor and operable to perform a prescribed working in accordance with the rotation of the rotor; wherein: at least one of a groove and a rib is provided on at least one of the inner circumference of the yoke and an outer circumferential circumference of the magnet so as to extend in an axial direction of the cylindrical yoke; and at least one of the groove and the rib is provided at a boundary between the magnetic poles.