PURPOSE: To reduce a weight of a carriage to realize reduction in size and light weight of an optical head by arranging a coil for focus control at the outside of the carriage.

CONSTITUTION: When a magnetic flux is generated in the direction of arrow mark C between a center yoke 18 fixed on a base 11 and a magnet 19, a drive force is generated in a coil 17 in the direction of arrow mark D with a mutual effect by a current flowing into a focus coil 17. Thereby, a carriage 13 coupled with the coil 17 moves also in the same direction. In this case, the other end of the carriage 13 is constrained by a plate spring 14 and the plate spring 14 elastically deforms like a cantilever putting a fulcrum on the coupling part 22 with a reference pin 15. Thereby, the carriage 13 and objective lens 1 displace in almost the vertical direction E of the magneto-optic disk surface 23 putting a rotation center on the coupling point 22 for the focusing operation. Therefore, mounting of focus motor 16 on the optical head is no longer necessary and weight of carriage 13 can be reduced.