A permanent magnet type synchronous motor includes an iron core rotor having a plurality of holes which are circumferentially spaced, permanent magnets mounted in the holes, an iron core stator and coils arranged in the stator iron core. The permanent magnets are defined by a flat surface extending tangentially of the rotor, tapered surfaces formed at both ends of the flat surface and extending obliquely outward in a direction approaching each other, and an arcuate surface joining the two tapered surfaces. Each permanent magnet is supported by tapered surfaces formed at opposing ends of the holes and extending obliquely and radially outward in a direction approaching each other. When the rotor is rotated, the centrifugal force is received at the tapered surfaces of the holes, rather than at their arcuate portion.