To provide an oscillator with a thermostatic oven which can be reduced in power consumption and size.

A crystal oscillating element 11 constitutes a resonator of a crystal oscillator. A heating element 13 is controlled for its heating by a heating element control circuit 14, to raise temperature in the vicinity of the crystal oscillating element 11. A thermostatic oven 16 stores the crystal oscillating element 11 and the heating element 13, and shields the crystal oscillating element 11 from outside temperature. On the inner wall of the thermostatic oven 16, a heat insulating paint 17 having heat insulating property is applied, to raise overall heat resistance of the thermostatic oven 16.