Provided is an anticorrosion device that does not require the installation of electrical equipment and has no concern about loss of anticorrosion effect due to deterioration of the anode. An anticorrosion device that prevents corrosion of a metal material in a structure, including a thermoelectric power generation unit 10 configured to generate an electromotive force due to a temperature gradient, an anode unit 20 that is responsible for an anode reaction corresponding to the electromotive force, and a cathode unit 30 that is responsible for a cathode reaction corresponding to the electromotive force, in which the cathode unit 30 is a metal material (target metal) in the structure.