PURPOSE: To avoid complexing of mechanisms by directly moving the substrate of a light source by means of a linear motor of simple constitution.

CONSTITUTION: The magnetic field A going to the direction orthogonal to the moving direction of a light source is normally held formed by using the magnets 13, 14, etc. sandwiched by respective yokes 11, 12 at both end parts in the longitudinal directions of the yokes 11, 12. In moving the light source 9, electric power is applied to a coil 10 to newly produce the magnetic field B going toward the direction orthognal to the moving direction of the light source 9 around the coil 10. The mutual action of these magnetic fields A, B gives the magnetical thrust force to the coil 10. An oscillating arm is oscillated by the movement of the coil 10, whereby the light source may be moved to the scanning direction.