An IPM motor for a vacuum pump suitable for use as a motor for a small vacuum pump is provided. The IPM motor for a vacuum pump includes: a rotor core in which a rotor shaft of the vacuum pump is pressed and which also has magnets embedded therein; and a stator core which surrounds the rotor core and around which stator windings are wound. The magnets per pole embedded in the rotor core are each split into two pieces and inserted in respective magnet slots in the rotor core. A hole for stress concentration relaxation is provided at either end of each pair of magnet slots in which permanent magnets split into two pieces are embedded in each pole. The rotor core has a multilayer structure having a plurality of rotor core laminations stacked vertically in an axial direction of the rotor shaft. The rotor core laminations stacked vertically are positioned with a skew angle determined by using the holes for stress concentration relaxation.