CuAlxGa1-xS2 crystals are grown by iodine transport method. Starting materials are constit-uent elements. The composition in the grown crystals, determined by electron probe X-ray mi-croanalysis, coincides approximately with that of the starting materials. Lattice constants follow Vegard's law. All crystals have p-type conduction and their resistivity decreases with increasing x. The composition dependence of the cathodoluminescence spectrum at77K and room temper-ature has been studied. The emission peaks are classified into certain groups. The highest-energy emission peaks observed for 0_??_x_??_0.74 at 77K are identified as the recombination of an exci-ton arising from a hole in the highest valence band, and an electron in the conduction band. The highest-energy emission peaks observed for 0_??_x_??_0.51 at room temperature can not be iden-tified as being due to the recombination of the exciton. The origin of the peaks is not clear. The peak positions observed for 0.2_??_x_??_0.4 at room temperature correspond to the blue region.