We have constructed the pseudo-binary phase diagram of the CaS-Ga2S3 system in order to prepare single crystals of CaGa2S4. Based on the diagram, single crystals doped with 0.1, 0.2, 0.4, 0.8 and 1.5 wt% Ce3+ are grown from melt by the horizontal Bridgman method. Photoluminescence spectra of these crystals are measured at room temperature. The overall features are in good agreement with the reported data of thin films. However, the emission intensity does not show a linear relation ship with doped Ce3+ concentration at more than 0.4 wt%, presumably because of the precipitates arising from the overdoping.