A rotary electrical switch for an automobile vehicle anti-theft device of the type comprising a rotor mounted free to rotate about a stator to supply electrical power to a starter, by at least one electrical strip contact, wherein the rotor comprises a surface acting as a cam to clean the electrical contact that cooperates with a portion facing the intermediate segment of a contact strip to elastically deform the contact strip globally in its median axial plane, causing relative displacement of the free lower end of the mobile segment with respect to the contact portion of the fixed contact element with which it is in contact, when the rotor closes or opens the electrical contact.