Provided is a navigation signal transmitter that can ensure, at low cost, that the frequency deviation of terrestrially transmitted navigation signals is reduced. A navigation signal transmitter receives a transmitted wave, generates sync pulses, which are synchronous with predetermined data frames, generates an internal clock fundamental oscillation by use of a reference signal synchronizing unit (550) with the sync pulses used as reference signals, generates an IMES signal on the basis of the internal clock fundamental oscillation, and transmits the IMES signal. The reference signal synchronizing unit (550) comprises a count circuit (551), a comparator (553), a low-pass control filter (554), a D/A converter (555) and a voltage controlled oscillator (556). The navigation signal transmitter is characterized in that when a relationship in magnitude between the number of clock pulses generated by the voltage controlled oscillator (556) with the sync pulses counted as the reference signals and a reference value successively occurs within a predetermined range of values in one direction a predetermined number of times, the reference signal synchronizing unit (550) is controlled to adjust the control voltage level of the voltage controlled oscillator (556).