II-VI laser diode was fabricated using a ZnCdSe/ZnS0.06Se0.94/ZnMgSSe SCH structure on GaAs, in which ZnMgSSe was originally proposed by our group. ZnMgSSe is lattice-matched to GaAs and the bandgap energy of ZnMgSSe is larger than that of ZnSe and ZnS0.06Se0.94 lattice-matched to GaAs. As for the crystal growth mechanism, the composition of ZnMgSSe is not changed and the RHEED pattern becomes spotty in group II-rich growth conditions and S incorporation is difficult in group VI-rich growth conditions. From these results, we consider that the optimized growth condition of ZnMgSSe is in the stoichiometric region (both (21) and c(22) were observed). As for the device quality, although the current density of this device is minimized to 500 A/cm2, it was difficult to improve the reliability of the electrode and the active layer ZnCdSe. We found that the thin ZnTe and thick ZnSSe based electrode is necessary for reliability of the electrode, and that an optimized VI/II ratio is necessary for the reliability of the active region. To fabricate a relatively low-operating-voltage device, the stripe width is also an important parameter. In spite of relatively weak covalent bond of II-VI compounds, we can produce a device lifetime as long as 400 h.