A permanent magnet having end surfaces and an envelope curve shaped as a biconvex lens having first and second convex portions, magnetization running in an arcuate manner along the first convex portion between a north pole and a south poles. The permanent magnet runs along the second convex portion in an arcuate manner, and at least one of the magnet's end surfaces within the envelope curve has a connection surface adapted for connecting with a connection device by fusing or by positive engagement. The rotor is preferably pressed onto the shaft of the rotor after the connection device is formed around a connection surface of the permanent magnets by injection molding.