To obtain a highly productive semiconductor laser with which the polarization mode of laser oscillation can be controlled by the amount of current injection.

A semiconductor laser has three or more divided current injection regions. At least one of the current injection regions has active layers 2 and 3 in a non-current injection state which form a refractive index waveguide structure of horizontal direction against a TM mode light, and they do not form the refractive index waveguide structure of horizontal direction against the TM mode light. At least one of other current injection regions has the active layers 2 and 3 in a non-current injection state which do not form a refractive index waveguide structure of horizontal direction against the TM mode light.