An image developing apparatus has a photosensitive body, an image-developing roller, a toner feeding roller, a housing cassette, whereon the image-developing roller and the feeding roller are mounted, for storing the toner, a plate-like blade mounted on the housing cassette, a sheet member for preventing the toner from leaking, and toner sealing devices made of a resilient material for preventing the toner from leaking. The sheet member is displaced between a development area of the developing roller and a position of the pressed contact between the developing roller and the feeding roller. The sheet member maintains a uniformly contact along a longitudinal direction of the developing roller. The toner sealing devices are either mounted integrally to, or formed integrally with the blade as one unit, and provided at both ends of the blade. A space is provided between the toner sealing devices and the housing cassette. The structure of this invention realizes prevention of the toner from leaking in the image developing apparatus, since it effectively fills a space between the blade and the developing roller. Furthermore, the structure also improves productivity and reduces working processes, since it makes adhesion of the toner sealing devices unnecessary in manufacturing the image-developing apparatus.