To improve a frequency temperature characteristic by providing a voltage generating means which has a cavity having a coil generating a magnetic field and a positive linear temperature coefficient characteristic and feeds prescribed voltage to the coil and a stimulation light generating means which supplies stimulation light to the cavity.

This rubidium atomic oscillator is provided with a cavity 1, a lamp part 2, a coil 3, a C-Field voltage generating part 4 and a control circuit 8. The coil 3 winds around the cavity 1, the cavity receives light from the part 2 adding exciting light and generates atomic resonance, and the coil 3 generates such a magnetic field as makes and atomic resonance frequency of the cavity 1 f0. The part 4 gives the coil 3 needed voltage. The variable resistor 6 adjusts so that the atomic resonance frequency of the cavity 1 can be f0, the resistor 9 changes voltage from the part 4 in accordance with the temperature change, and the control circuit 8 outputs the resonance frequency from the cavity 1.