To enhance the reliability and precision of a digital temperature compensation oscillator by decreasing fluctuation in the output of the oscillator due to the noise characteristics of a temperature sensor and an A/D converter.

In the digital temperature compensation oscillator having a temperature sensing means 31, an A/D converter means 32, a storage means 34 and an oscillation means 36, whether temperature data outputted from the A/D converter means 32 are first sampling data is checked. When the temperature data are the first sampling data, the temperature data outputted from the A/D converter means 32 are set as a temperature code to obtain the temperature compensation data without any modification and given to the storage means 34. When the temperature data are not the first sampling data, the temperature data outputted from the A/D converter means 32 are accumulated by a prescribed sampling number of times, and their mean value is stored by the storage means 34 as the temperature code to obtain the temperature compensation data.