To provide a semiconductor light emitting element, in which a strain does not exist in an active layer, and in which the band gap difference between the active layer and a clad layer is large.

An n-type clad layer 5, a first guide layer 6, an active layer 7, a second guide layer 8 and a p-type clad layer 9 are laminated sequentially on a substrate 1 composed of n-type GaAs. The n-type clad layer 5 and the p-type clad layer 9 are composed of a ZnMgSSe mixed crystal. The first guide layer 6 and the second guide layer 8 are composed of a ZnSSe mixed crystal. The active layer 7 is composed of an AlGaAs mixed crystal. Since the band gap of a III-V compound semiconductor is small as compared with that of a II-VI compound semiconductor, the band gap difference between the n-type clad layer 5 and the p-type clad layer 9 and the active layer 7 can be made large, and an overflow current can be suppressed. In addition, the active layer 7 is lattice-matched to the substrate 1. As a result, the crystallinity of the active layer 7 can be enhanced, and the characteristic of a semiconductor light emitting element can be enhanced.