According to an embodiment of the invention, a heat uniforming member, which has an outer diameter smaller than an inner diameter of a hollow member and in which thermal deformation generated by thermal expansion remains, is set in the inside of the hollow member having a center axis, support members are set to both ends of the hollow member to enable supporting of ends of the heat uniforming member, and an endless body having a uniform thermal distribution is formed by heating the hollow member, the heat uniforming member and the support member at a specified temperature for a specific time and causing the heat uniforming member to adhere closely to an inner wall of the hollow member.