A synchronization device has a normal-signal generator, a reference-signal generator, and a phase difference detector. The normal-signal generator generates a normal signal whose timing is synchronized with a time signal from a satellite. The reference-signal generator generates a reference signal whose timing is synchronized with a received signal. The phase difference detector detects the phase difference between the reference signal and the normal signal. The normal-signal generator then controls the normal signal on the basis of the phase difference when the time signal cannot be obtained.