This interior permanent magnet electric motor is equipped with a stator and a rotor (21) having a rotor core (23). The rotor core (23) has a plurality of first steel plates (30) and second steel plates (31). The plurality of first steel plates (30) are stacked together in the direction of the axial center (27a) of a rotary shaft (27). Each first steel plate (30) includes a first flat section (30a) in which a plurality of magnet holes (22) are formed. The second steel plates (31) are positioned on the ends of the stacked plurality of first steel plates (30) in the direction of the axial center (27a). Each second steel plate (31) includes a second flat section (31a) and extension parts (25). A plurality of magnet holes (22) are formed in the second flat section (31a). The extension parts (25) extend from the second flat section (31a) toward respective magnet holes (22). The thickness of the extension parts (25) in the direction of the axial center (27a) is smaller than that of the second flat section (31a).
