A self-powered portable electronic device includes a main body, a cover slidably assembled on the main body, a sliding part secured on the cover, and a power generating device. The power generating device includes a rack secured on the sliding part, a power generating module assembled on the main body, and a gear engaging the rack and assembled on the power generating module. The cover slides the rack relative to the main body, and the gear is rotated by the rack and drives the power generating module to generate operating power.