To reduce the production cost of an elevator facility by accurately detecting the rotational speed and the magnetic pole positions of a motor body without disposing a pulley and a pulse generator around a rotating shaft and generating triangular wave signals showing the magnetic pole positions to reduce the number of peripheral signal transducing circuits such as a PLL circuit.

A machined face 10 having a curvature as shown in the expression 1 through a length 'R1' from the center of the rotating shaft 9 is formed on the outer peripheral surface of the rotating shaft 9 with a cycle of 360/(2P)°. An optical range finder 12 is disposed so that a distance from the center of the rotating shaft 9 to an optical signal input/output window 11 is 'r1+B1'. A distance 'Y1' between the optical signal input/output window 1 of the optical range finder 12 and the machined surface 10 is measured, and serrated detection signals are outputted.