A phase comparing unit compares a phase of an imaging-side synchronization signal with a phase of a display-side clock, and controls oscillation of a display-side clock generating unit based on a result of the comparison. A display timing adjusting unit receives a video signal output from an endoscope at a timing based on the imaging-side synchronization signal and adjusts a synchronization timing of the received video signal to a synchronization timing based on a display-side synchronization signal.
