An electronically controlled thermostat device simplifies an insulating structure and external portions of the lead wires of a heater incorporated for temperature control of a thermo-element, reduces the number of different parts, and facilitates assembly. A pair of insulating rod pieces clamps the heater at the front and clamps a pair of lead wires from the heater while maintaining an insulated state, and a connector member attached to a side of the insulating rod pieces opposite the portion that holds the heater is mounted on the outside of a device housing. The connector member at an inner end has connector terminals provided with a pair of lead end connecting pieces to which the lead wires are connected, and has an engaging concave portion that engages an engaging convex portion for preventing twisting provided on a side of the insulating rod pieces opposite the portion that holds the heater.