An optical head includes a fixed part, a movable part movably held by a plurality of wires fixed on the fixed part, and magnets fixed to the fixed part. The movable part includes a movable-part housing, a heatsink held by the movable-part housing, a light emitting element and a light receiving element both mounted on the heatsink, magnets provided to both sides of the movable-part housing to contact the heatsink, an objective lens held by the movable-part housing to allow an emitted laser beam from the light emitting element to focus, and a diffraction grating provided between the objective lens and the light emitting element and between the objective lens and the light receiving element. The gap between each coil and the adjacent magnet is filled with ferrofluid having a higher thermal conductivity than the atmosphere.