The invention provides an image-forming apparatus equipped with a toner container containing toner particles and an endless belt circulating in contact with image carriers carrying electrostatic latent images. The image-forming apparatus forms a toner image on a recording medium by developing an electrostatic latent image on an image carrier by supplying the toner particles thereto, transferring the toner image onto the surface of the belt and finally onto the recording medium, and fixing the toner image thereon. When the particle count distribution in diameter ranges of the toner particles is expressed by Smaller-side grain size distribution index GSDpS=(D50p/D16p)1/2, the toner container contains toner particles having a smaller-side grain size distribution index GSDpS of 1.24 or less; and the belt comprises a base support having a Young's modulus of 3,500 MPa or more and 9,000 MPa or less and a surface microhardness of 10 mN/μm2 or less.