PURPOSE: To obtain a miniature crystal oscillator having a thermostatic chamber by using a laminated sintered body, a crystal oscillator, an active element, a thermistor and a means which insulates heat and preserves all said component elements.

CONSTITUTION: A crystal oscillator having a thermostatic chamber is provided with a sintered body 100A containing a laminated ceramic of a resistance, a heater and a capacitor, a semiconductor 200A of a transistor, etc. which is formed on the body 100A, a thermistor 27, a crystal oscillator 22, a lead terminal 300A which supplies a current to the body 100A, a metallic case 400A which stores the body 100A, and a heat insulator 500A which is packed into the case 400A. In such a constitution, it is possible to obtain a miniature crystal oscillator having a thermostatic chamber.