In this paper we propose a mechanical rectifier for micro electric generators. Since micro electric generators usually produce alternating-current power, innovation ideas for DC outputs are strongly demanded. Electric rectifiers are one of solutions; however, electric rectifier circuits using semiconductor elements have a threshold voltage. It means that the electric generator has to generate higher voltage than the threshold or needs initial external energy for correct operations. Our idea is to use a mechanical rectifier fabricated by MEMS techniques. In this paper a seismic generator with an electret are employed as a micro electric generator. A micro cantilever doubles as a counter electrode for the electret and a mechanical switch in an electric rectifier circuit. we discuss the feasibility for the mechanical rectifier using the micro cantilever and confirm the validity of the whole system by a basic experiment.