To smoothly compensate the temperature of a quartz resonator even near an inflection point correspondingly to the temperature characteristic of the resonator which draws quadratic and cubic curves.

The temperature of a quartz resonator is collectively compensated by giving the higher-order bits of digital information obtained by A/D- converting the analog information of a temperature sensor 1 to a storage circuit 3 storing temperature correcting information as reading-out addresses and the lower-order bits to a capacitor switch control circuit 8 which performs temperature compensation as analog values after the lower-order bits are inputted to an inverting circuit 6 which inverts the order of the lower-order bits.