We propose and implemented a novel structure and fabrication method of a micro energy harvesting device based on vibration-driven power generation that matches the surrounding oscillation frequency. When the micro energy harvesting device vibrates at its own resonant frequency, its output maximizes. However, a micro device usually has a high resonant frequency, because of the size. We succeeded in lowering the resonant frequency without scaling-up the device using Si micromachining technology. We propose a structure in which a polymer with a low Young's modulus is embedded in a Hybrid Silicon Micro Structure (HSMS). We applied the structure to a micro cantilever generator with an electret that is 3.5 mm long, 1.0 mm wide and 115 μm thick. We demonstrated that the HSMS generator has a low resonant frequency and consequently is efficient at low frequencies.