A rotor for an electric motor, comprising: a rotor core constructed by punching out lamination plates into a predetermined shape and laminating a predetermined number of the lamination plates; and a plurality of sets of two flat-shaped permanent magnets, each set constituting a magnet pole, each of the two permanent magnets having a cross-sectional face with a shape of a rectangle having first and second chamfered corners on opposing ends of one long side of the rectangle, wherein the rotor core is provided with a plurality of substantially V-shaped cavities each forming a convex shape along a magnet pole central line inwardly in a radial direction of the rotor core and extending to a vicinity of an outer peripheral portion of the rotor core on two sides of the magnet pole central line, and wherein the two permanent magnets of each set are inserted in a corresponding one of the cavities such that one of the two permanent magnets in each set is located on one side of the magnet pole central line of the corresponding one of the cavities, the other one of the two permanent magnets in each set is located on an opposite side of the magnet pole central line of the corresponding one of the cavities, the one long side of the cross-sectional face of each of the two permanent magnets is located more outwardly in the radial direction of the rotor core than the opposite long side of the rectangle, characterized in that the lamination plates are silicon steel lamination plates and in that end portions of the two permanent magnets closest to the magnet pole central line come into contact with each other on a point along the magnet pole central line of the corresponding one of the cavities. a rotor core constructed by punching out lamination plates into a predetermined shape and laminating a predetermined number of the lamination plates; and a plurality of sets of two flat-shaped permanent magnets, each set constituting a magnet pole, each of the two permanent magnets having a cross-sectional face with a shape of a rectangle having first and second chamfered corners on opposing ends of one long side of the rectangle, wherein the rotor core is provided with a plurality of substantially V-shaped cavities each forming a convex shape along a magnet pole central line inwardly in a radial direction of the rotor core and extending to a vicinity of an outer peripheral portion of the rotor core on two sides of the magnet pole central line, and wherein the two permanent magnets of each set are inserted in a corresponding one of the cavities such that one of the two permanent magnets in each set is located on one side of the magnet pole central line of the corresponding one of the cavities, the other one of the two permanent magnets in each set is located on an opposite side of the magnet pole central line of the corresponding one of the cavities, the one long side of the cross-sectional face of each of the two permanent magnets is located more outwardly in the radial direction of the rotor core than the opposite long side of the rectangle, characterized in that the lamination plates are silicon steel lamination plates and in that end portions of the two permanent magnets closest to the magnet pole central line come into contact with each other on a point along the magnet pole central line of the corresponding one of the cavities.