A thin-type optical head, smaller in optic mounting spaces comprising to the conventional one, in an optic system enabling with BD including a 2-layers BD, DVD an CD, comprises a light source, for emit a light beam therefrom; an optical branch element for penetrating a predetermined amount of lights, therethrough, of an incident light beam thereon, and to reflecting remaining amount of lights thereupon; a light focusing element for focusing the light beam upon an optical information recording medium; a photo detector for receiving the light beam reflecting upon the optical information recording medium; and an optical path converter element for converting an angle of an optical path, on which the light beam propagates, wherein the optical path converter element is disposed on an optical path of the light beam between the optical branch element and the photo detector, or between the optical branch element and the light source, and has an incident surface, upon which the light beam enters, and an emission surface, from which the light beams emits, so that the light beam reflects at least two (2) times within the optical path converter element, during time when passing through between the incident surface and the emission surface.