PURPOSE: To make it possible to obtain a high output even under the effect of a spatial hole-burning penomenon by a method wherein the reflectance of an antireflection(AR) coat is optimized taking a matter that the density distribution of carriers in a semiconductor laser is ununiformized due to the spatial hole-burning phenomenon into consideration.

CONSTITUTION: A low-reflectance film 30 is formed on the end surface on one side of the end surfaces of arc active layer 16, a high-reflectance film (an HR coat) 32 is formed on the other end surface and a resonator is constituted of these films. In this case, when the reflectance R0 of the AR coat 30 is shown by α1 L (Provided that, the α1 is the absorption factor of the layer 16 and the L is a resonator length on the layer 16.), the low reflectance R1 of the AR coat 30 is set within a range of R0/2<R1<2R0. Moreover, an electrode, through which a current is injected in the layer 16, is split into at least an electrode on the side of the film 32 and an electrode on the side of the film 30 and a current I1, which is injected through the electrode 34 on the side of the film 30, is made higher than a current I2, which is injected through the electrode 36 on the side of the film 32. Thereby sufficiently high output characteristics are obtained in consideration of the density distribution of carriers in the direction of the resonator.