A position detecting device includes an optical position detecting element and a position information portion which are disposed so as to be opposed to each other. The position information portion has a binary pattern where a high light efficient portion and a low light efficient portion are alternately repeated when the movable portion moves in a predetermined direction. The position detecting device includes a loose position detecting portion for detecting a loose position of the movable portion by counting a pulse signal obtained by the optical position detecting element, a close position detecting portion for detecting a close position of the movable portion by counting pulse number of driving pulses which are applied to an electromechanical transducer from a position where the loose position detection is carried out, and a combining arrangement for combining the loose position with the close position to calculate a current position of the movable portion.