To provide a synchronous oscillation apparatus and synchronous oscillation method in which a reference oscillation frequency is allowed to have accuracy, equal with or higher than a fixed level compensating for aging, without using a highly accurate oscillator even at self-traveling time, even if the ambient temperature changes.

A synchronous oscillation apparatus according to the present invention measures a temperature around a voltage controlled oscillation unit and records, in a predetermined cycle, temperature compensation data containing the measured temperature and a control voltage at the time of measuring the temperature. Furthermore, if meeting predetermined conditions, for example, if a signal for synchronization can not be received, the synchronous oscillation apparatus controls the control voltage based on the temperature compensation data.