To suppress the consumed electric energy of a high accuracy reference oscillator such as an atomic oscillator and a constant temperature oven controlled crystal oscillator.

Upper frames 71, lower frames 72, side face upper frames 73, and side face lower frames 74 each having thermal insulation performance fix a cell 41 inside a capsule 40 in an oscillation section 31 which an atomic oscillator includes, a heater driving body 47 is provided on each of heaters 43 for heating the cell 41, and the heater driving body 47 allows each heater 43 to be in contact with the cell 41 at heating of the cell 41 and separates each heater 43 from the cell 41 in the case of not heating the cell 41.