The vibration in AC-PDPs was investigated to understand the relationship between electric and mechanical oscillations. The vibration peaks from AC-PDPs were observed at 4900, 9750, 14650, and 19550Hz. These peaks were corresponded to the frequency components of applied power. The vibration intensity at different peaks was linearly increased with rising applied voltage regardless of discharge, and this implied the effects of discharge on vibrations were very small. From these results, the origin of vibrations in AC-PDPs was mainly the electric field due to displacement current.