Piezoelectric buzzer for energy harvesting was investigated. While external force was applied to a buzzer, PZT unimorph in the buzzer, the ceramic disc dimensions and capacitance of which were 14 mm in diameter, 0.2 mm in thickness and 10 nF, generated resonance vibration. As a result, an alternating voltage with the value of around 30 V and the frequency of 5 kHz was observed. After rectifying, the voltage was applied to LED, and new devices such as night-view footwear were developed. It was confirmed that the energy harvesting utilized resonance phenomena is one of an effective tool to obtain clean energy. This work was partially supported by a Grant 2010 of B-nest at Shizuoka City, a Grant-in-Aid for Scientific Research C (No. 21560340) and a Grant of Strategic Research Foundation Grant-aided Project for Private Universities (No. S1001032) from the Ministry of Education, Culture, Sports, Science and Technology.