<p>Provided is a small-size and highly stable oscillator which can easily correct a frequency shift caused by a temperature fluctuation. The oscillator includes: an overtone crystal unit (11) of three or higher dimension; an oscillation circuit (12) which is connected to the crystal unit (11) and outputs an oscillation frequency; a divider (13) which divides the oscillation frequency and outputs the divided frequencies to a system device processing unit (2); a temperature sensor (16) which detects a temperature around the crystal unit (11); and a memory (17) which stores information for correcting a frequency shift of an oscillation frequency according to the temperature characteristic of the crystal unit (a coefficient of an equation for calculating a correction amount of a frequency shift or the frequency shift corresponding to the temperature) and provides information to be used for correcting the frequency shift to the system device processing unit (2).</p>
