PURPOSE: To provide a displacement information detecting device which can be made small in size without the deterioration of the accuracy in detection, a drive control device using the detecting device, and a scale device being suitable for the displacement information detecting device, in an apparatus wherein optical systems based on different principles of detection are provided together.

CONSTITUTION: In an apparatus wherein the information on rotation of a scale member D is detected by detecting the information on the interference of diffracted light generated by radiating a light flux to a diffraction grating GT provided on the scale member D, a constitution for detecting light from data recording parts Z1, Z2, U, V and W so as to detect the information on rotation of the scale member D is provided separately and the diffraction grating GT and the data recording parts Z1, Z2, U, V and W on the scale member D are formed by different manufacturing methods.