Unsaturated polyester resin (UPR) is generally cured by room temperature curing method using oxidationreduction reaction between curing agents and accelerators. However, it is difficult to realize the maximum physical properties within a short time only by room temperature curing process. Therefore, post-curing process should be carried out to improve physical properties. In this study, post-curing of room temperature-cured UPR was carried out by electron beam irradiation and the physical properties of the post-cured samples were compared with those of thermally post-cured samples. As a result, the physical properties of room temperature-cured UPR were increased with an increasing electron beam absorbed dose and were comparable to those of thermally post-cured UPR samples. Thus, electron beam curing method can be applied to the mass production of UPR-based products instead of conventional thermal curing method.