Disclosed is a semiconductor laser device comprising a layered semiconductor region capable of laser oscillation and including at least an optical confinement region consisting of stacked semiconductor layers, means for injecting current into the optical confinement region, and means for constructing an optical resonator; switching means for supplying the layered semiconductor region capable of laser oscillation with a current having a value near a threshold current value for the laser oscillation; and switching means for feeding a current to be superposed on the current supplied to the layered semiconductor region capable of laser oscillation, this switching means being capable of controlling the current to be superposed through an external input thereof.