PURPOSE: To realize a low threshold value by changing thickness of a semiconductor layer on a MESA protrusion having a constant width or thickness of a semiconductor layer within a MESA groove having a constant width and then providing active layers in different wavelengths of emitted light.

CONSTITUTION: A MESA protrusion 2M is formed on the main surface 1S of a semiconductor base material 1 and width Wg1 of the MESA groove 2G provided between MESA protrusions 2M is changed with the width Wm thereof maintained to a constant value. Or, width Wg of the mesa proove 2G is maintained to a constant value and width Wm1 of MESA protrusion is changed to form the parallel arrangement thereof. A semiconductor layer consisting of at least a first clad layer 4, an active layer 5 having a quantum well structure and a second clad layer 6 is sequentially epitaxially grown on the entire part including the MESA protrusion 2M to form an eptiaxial growth layer 10. The active layers 5 in different wavelengths of emitted light are provided by changing thickness of a semiconductor layer 19 on the MESA protrusion 2M or that within the MESA groove 2G.