Piezoelectric materials have been investigated as vibration energy converters to power wireless devices or MEMS devices due to recent low power requirement of such devices and the development of miniaturization technology. It has shown the potential that piezoelectric power generator can be an alternative to the traditional power source-battery because of facile vibration sources in our environment and the potential elimination of maintenance required for large volume batteries. To date, PZT (Lead Zirconium Titanate) has been commonly exploited as a piezoelectric material for energy conversion since it can generate higher power density even at low-g (< 1 g) vibration environment. Its high fragility, however, can limit its applicability at high-g conditions. Therefore, other types of piezoelectric materials such as polymer and composite are necessary to investigate the applicability at severe vibration conditions. In this study, piezoelectric power generators based on cantilever beam structure were designed, optimized, and fabricated by considering matching the resonant frequency with environmental vibration, achieving maximum output power, and reaching maximum g-value without device failure. As piezoelectric materials, ceramic PZT, polymer PVDF (Polyvinylidene fluoride) and composite MFC (Macro Fiber Composite) were utilized. The energy conversion of all three types of generator devices was systematically evaluated. All three devices were measured to generate enough power density for providing electric energy to wireless sensor or MEMS device. The PZT device shows the highest output energy density and PVDF device has the highest durability to operate at high-g vibration condition.