To provide a charging device and a charging method for partially charging an electret by corona discharge treatment and capable of sufficiently increasing a potential difference between a charging region and non-charging region of the electret, and a vibration power generating device.

A charging device of an electret includes: a lower electrode 8 arranged below an electret 9 and connected to a ground potential; a discharge electrode 12 isolated above the lower electrode 8 for corona discharge treatment; a voltage source electrically connected to the lower electrode 8 and the discharge electrode 12, for applying voltage to the lower electrode and the discharge electrode; a mask 11 made of a conductive material and disposed on the electret 9 and in which a through-hole is formed; and a voltage controller 13 for performing control so that a potential difference between the mask 11 and the ground potential becomes a voltage set to be larger than 0 and smaller than the absolute value of a breakdown voltage of the electret 9.