A charging device for applying a voltage to a latent image carrier of an image forming apparatus includes a brush roller, a voltage applying mechanism, and a driving mechanism. The brush roller includes a shaft and a brush. The brush has an oblique brush amount, and is disposed on an outer surface of the shaft while being disposed to a surface of the latent image carrier such that the brush roller is abutted with a brush contact amount. This brush is configured to uniformly charge the surface of the latent image carrier. The voltage applying mechanism is configured to apply a charging voltage to the brush roller. The driving mechanism is configured to drive the brush roller at a predetermined rotation number to satisfy a relationship Z>150-50 A, where Z is a rotation number (rpm) of the brush roller, and A is the oblique brush amount (mm).