The inventive concept provides MIT devices molded by clear compound epoxy and fire detecting devices including the MIT device. The fire detecting device is supplied with a power source from a power control device. The fire detecting device includes a MIT device including a MIT chip molded by a clear compound epoxy, a diode bridge circuit supplied with the power source from the power control device for providing a non-polar power source, a notice circuit supplied with the non-polar power source from the diode bridge circuit for warning of a fire alarm in response to a detecting signal from the MIT device, and a stabilization circuit for maintaining the detecting signal for a certain period.