Abstract: In an optical head, a semiconductor laser is supported on a base and the base is secured to a hollow frame. A lens-barrel for supporting collimator lens system is disposed in the hollow frame so that the collimator lens system is faced to the semiconductor laser. The frame and lens-barrel are secured in point contact securement to each other by studs screwed in dies provided on the frame. The base, lens-barrel and frame are made of materials having linear expansion coefficients satisfying either one of inequalities .alpha..gtoreq..gamma..gtoreq..beta. and .beta.>.gamma.>.alpha., where .alpha., .beta. and .gamma. are linear expansion coefficients of the base, frame and lens-barrel respectively.