Rotor of electric motor

There is disclosed a rotor of an electric motor, which can decrease the generation of noises. In the rotor of the electric motor, comprising a rotor core formed by laminating a plurality of iron plates for the rotor; insertion holes corresponding to magnetic poles of the rotor core and provided along the axial direction of a rotary shaft; and a pair of flat plate-like permanent magnets inserted into each of the insertion holes to constitute the magnetic pole, the insertion holes are formed into such a V-shape as to project toward the outer periphery of the rotor core, and 0 < t1/t2 ‰¤ 0.15 is satisfied in which t1 is the shortest distance from the outer end of the insertion hole to the outer periphery of the rotor core and t2 is a width dimension of each of the permanent magnets.