A brush charging device for an image forming apparatus, which charges a surface of an image carrier rotating in a predetermined direction, has a linear mount member, a base cloth mounted on the mount member and a brush member having fibers mounted on the base cloth at an angle .theta..sub.1. The angle .theta..sub.1 satisfies the following formula: cos.theta..sub.1 >c/(a+b) wherein a represents the radius of the image carrier, b represents the length of the brush fibers and c represents the distance between a point of intersection where a perpendicular line extending from the center of the image carrier to the base cloth intersects the base cloth and an edge portion of the base cloth located upstream going in the direction of the image carrier, and where the brush fibers contact the surface of the image carrier.