To provide a method for manufacturing a heat-resistant endless belt less in degradation of adhesive strength even if heated to a high temperature, high in strength of a joint part at 190°C and having no influence on an image caused by the joint part in the case of being applied to an image forming apparatus.

The method for manufacturing a heat-resistant resin belt includes an inclined thin-walled part forming process for forming inclined thin-wall parts at both ends of a heat-resistant sheet, an adhesive applying process for applying an adhesive composition to the inclined surfaces of the inclined thin-walled parts by a screen printing method, a sticking process for sticking the inclined surfaces to each other, and an adhesive curing process for curing the adhesive composition. An additive polymerized silicon adhesive composition containing 6.5-9.9 wt.% ferric oxide (III) in a solid component is used as the adhesive composition. A viscosity at 23°C before curing the additive polymerized silicon adhesive composition is 50-100 Pa s, and an elongation when cutting in a tension test after curing the adhesive composition is 250% or more.