A step-by-step electric relay structure of a bistable type, comprising a mechanical part and an electric part, the mechanical part comprising push-button means to be operated by a user and the electric part comprising coil means, capacitor means, resistor means and diode means operatively interconnected to one another, the coil means comprising either two coils coupled in parallel to one another or a single coil polarized or biased with two polarities, thereby, as the push-button means are operated by the user to provide a switching or exchanging of at least a contact of the relay structure, either one of the two coils is shorted or the two polarities of the single coil are mutually reversed, thereby providing the electric relay structure with a logic SET function and a logic RESET function.