PURPOSE: To obtain a semiconductor laser fitted with a light modulator and the manufacturing method thereof wherein the laser beam generated in the active layer of the semiconductor laser propagates efficiently through the light absorbing layer of the light modulator.

CONSTITUTION: A stripe-like groove 1a is formed in a part of an n-type InP substrate 1, and in this groove 1a an n-type GaInP layer 2 is made to grow in a buried way. Subsequently, on the n-type InP substrate 1, an n-type InP buffer layer 3, an undoped InGaAsP layer 4, and a p-type InP layer 5 are subjected in succession to epitaxial and thereafter, these respective layers are patterned. As a result, a mesa stripe part 50 comprising the part (3b, 4b, 5b) grown on the n-type GaInP layer 2 and the part (3a, 4a, 5a) connected with the part (3b, 4b, 5b) grown on the different region from the n-type GaInP layer 2 is formed. Then, the part (3b, 4b, 5b) is used as the active layer of a light modulator and the part (3a, 4a, 5a) is used as the active layer of a semiconductor laser.