The diffuse reflection, excitation and fluorescence spectra of Ce3+ ions in Y3Ga5O12 garnet phosphor have been studied and discussed at room temperature for the first time. It has been found that the YGG:Ce3+ shows the optical properties of the allowed 5d-4f transition of Ce3+ ions whether under UV radiation or visible blue light or oathoderay excitation. The broad emission band extending from 430 to near 670 nm results from the transition of the lowest 5d level to 2FJ (J=5/2, 7/2) terminal state. In YGG, the optical behaviour of Ce3+ Is very similar to that of Ce3+ In YAG, but the positions of absorption and emission bands of Ce3+ shift toward shorter wavelengths.