A transfer residual toner that has not been electrostatically transferred onto a transfer paper P at a transfer nip and remains on a surface of a photosensitive element is temporarily retained by an elastic blade of a toner retaining unit in a mechanical manner before reaching a latent image forming area. The base material, in area of the front-side layer on which the heating conductor is laid and fastened, has a lower compression hardness andor a volume density than does this base material in the area of its opposite, rear-side layer. The round window driving transducer can be placed inside the middle ear cavity, radiate sound with high efficiency, and be implanted by surgery using a fixing part formed with shape memory alloy, shape memory resin, or a bendable spring structure.