An image forming apparatus includes a toner image forming portion, an endless belt, first, second, and third rollers, and an urging roller, and satisfies: 25 (mm)>X>(R1+R2)2−(R1−R2)2)1/2−L1)+7 (mm), 3.5 (mm)≧Y>0.5 (mm), and L1>0 (mm). X is a distance between Lb passing through a rotation center of the third roller and perpendicular to an outer common tangential line L between the first and second rollers and Lc passing through a rotation center of the urging roller and L, R1 is a radius of the first roller, R2 is a radius of the urging roller, L1 is a distance between Lb and a line La passing through a rotation center of the first roller and L, and Y is a distance between L and a tangential line Ld of the urging roller parallel to L.