Abstract: An electric potential therapy device includes a negative voltage applying means, an electrostatic charge removing means, and a controller that controls the negative voltage applying means and the electrostatic charge removing means in a predetermined therapy time in which a therapy cycle is repeated a plurality of times, the therapy cycle consisting of a first and second period. The negative voltage applying means includes a negative voltage generator and an application electrode. The negative voltage generated by the negative voltage generator is applied to the living body through the application electrode. The controller charges the living body to a negative potential in the first period by controlling the negative voltage applying means to apply the negative voltage to the living body, and puts the living body into a non-charged state by controlling the electrostatic charge removing means to remove electrostatic charges from inside the living body in the second period.