The roller member has a substrate and an electroconductive elastic layer. The elastic layer has a crown shape of which an outer diameter at the middle in the lengthwise direction is larger than those at its both ends. The elastic layer includes a bowl-shaped resin particle. The surface of the roller member has concavity derived from an opening of the bowl-shaped resin particle and a protrusion derived from an edge of the opening of the resin particle. The relation in the restoring rate for elastic deformation between at the middle of the roller member and at its both ends is such that: on the surface of the elastic layer the restoring rate is larger at both ends than that at the middle, and at the position of depth t μm from the elastic layer surface the restoring rate is larger at the middle than that at both ends.