In a toner case attachable to and detachable from a case storage portion of an image forming apparatus, a case main body is long in an attachment direction with respect to the case storage portion, and includes lower and upper housings defining lower and upper spaces among its inner space. Rims of upper-surface opening of the lower housing and lower-surface opening of the upper housing are joined together. A ceiling surface of the case storage portion is inclined diagonally upward from upper end of one side wall of the case storage portion toward the other opposite side wall in the width direction. The upper housing includes an inclined portion inclined corresponding to the inclined surface. When the case main body is attached to the case storage portion, the joint portion of the lower and upper housings has approximately the same height as the upper end of the side wall.