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, and each of light heating sections 43 emits light to the cell 41 to heat up the cell 41.