PURPOSE: To increase the accuracy of the crystal watch by switching the two output signals based on the detection information on the difference and the scale of the frequencies of the two crystal oscillator circuits featuring the different temperature- frequency characteristics.

CONSTITUTION: Rectangular wave signals P1 and P2 featuring the temperature- frequency characteristics f1 and f2 of crystal oscillator circuit 1 and 2 are changed into output signal P3 the frequency of which is equal to beat frequency fB of f1 and f2 in case the phase difference is zero at phase detector circuit 3 and then supplied to compensation control circuit 9 to undergo 1/n by divider circuit 4 and then to be changed into signal P4. Then α timer 6 counts the units of signal P3 and transmits signal P5 to signal switch circuit 8. And the transmission of P5 is stopped when the number of the signals reaches α to start β timer 7. Timer 7 transmits signal P6 to circuit 8 only for the time of β=n.B to fixed time B second. And circuit 9 transmits signal P8 to circuit 8 so that the output period of signals P5 and P6 may be the correction time and at the same time performs the switching between signals P1 and P2 through the count unit designation of timer 6 plus circuit 8 and by signal P7 sent from speed decision circuit 5 which desides the scale of the frequencies of signals P1 and P2.