A rubber roller, for use in an image-forming apparatus, which is formed by molding a rubber composition into the shape of a roller. In the rubber roller, a complex elastic modulus E* of rubber and a surface roughness Rz of the rubber roller satisfy a relationship indicated by an equation (1) shown below; and a hardness change of the rubber is set to not more than five points when the rubber ages at 70.degree. C. for eight days: 7.times.Ln E*-0.12.times.Rz+3.0.ltoreq.10. Equation (1)