PURPOSE: To provide an electrolytic rust inhibiting device with the consumption of power reduced and to further improve the rust inhibiting effect.

CONSTITUTION: This device is formed with an electrode 2 provided to an object 10, a pulse power source unit 6 for constituting a pulse power source from the DC power source supplied from a DC power source unit 1 and supplying the current of the pulse power power source to the object 10 through the electrode 2, a moisture sensor 3 to output a detection signal corresponding to the amt. of moisture depositing on the object 10 and a means 4 to control the supply of the pulse current in accordance with the magnitude of the detection signal outputted from the sensor 3. The sensor 3 is formed with the material having a greater ionization tendency than the object 10, and the sensor 3 and electrode 2 are housed in an electrode unit 5 close to each other.