A single-plate color projector includes a color wheel for chromatically separating light emitted from a light source in time series. An image forming device optically modulates each separated color light in sequence. A driving mechanism rotates the color wheel in a circumferential direction. A reflective marker is rotated together with the color wheel. A detector circuit detects movement of the reflective marker to generate a signal. A driving mechanism control circuit drives the driving mechanism in synchronization with the signal generated by the detector circuit. An image forming device control circuit drives the image forming device in synchronization with the signal generated by the detector circuit, and a time adjusting mechanism moves either the reflective marker or the detector circuit or both the reflective marker and the detector circuit to change a relative positional relationship therebetween.