In a self-pulsation type semiconductor laser, a first clad layer of a first conductivity type, an active layer, and a second clad layer of a second conductivity type having a striped ridge portion are successively stacked on a semiconductor substrate of the first conductivity type. In an embedding layer formed on either side surface of the ridge portion and on either flat portion other than the ridge portion of the second clad layer, a saturable absorption layer is provided on a material layer having a refractive index equal to or greater than that of the second clad layer and not absorbing laser light.