PURPOSE: To grow a third clad layer without oxidizing the surface of a second clad layer, and improve crystallinity, by a method wherein a thinnly left layer of a current constriction layer is vaporized until it reaches the second clad layer, by performing heat treatment in an AsH atmosphere before the third clad layer is formed.

CONSTITUTION: A current constriction layer 7 above an active layer 3 which corresponds to a light emitting region is so etched that a thin layer 7a is formed while the layer 7 of about 0.057μ in thickness is left. After photoresist 10 which has been used for patterning is eliminated, the element is put in an MOCVD equipment while the thin layer 7a is left as it is, and heat treatment at 900-1050°C is performed for 60 minutes in an arsine atmosphere wherein the partial pressure of AsH4 is 3×10-4. Thereby the thin layer 7a left in the current constriction layer 7 is vaporized, and a clean surface of the second clad layer 4 is exposed, so that troubles due to an surface oxide film on the second clad layer are not generated.