To provide an inexpensive and easily-installable submergence detection device.

In this device, two temperature detection circuits 16A, 16B are used. Each of temperature detection circuit 16A, 16B comprises a mechanism for detecting a potential between a thermistor 20A, 20B and a potential dividing resistance element 22A, 22B connected in series between a power source 18 and the ground. The thermistors 20A, 20B in the two temperature detection circuits are arranged with the difference of height h in a easing 10 wherein submergence is to be detected. When the submergence is generated, the temperature of the lower-side thermistor 20A is lowered, and the difference of output voltages of the two temperature detection circuits 20A, 20B is changed, to thereby detect the submergence.