Provided are a HCV particle formation promoter capable of promoting formation of HCV particles in culture cells, and a method of enhancing production of HCV particles. Also provided are a method of evaluating an anti-HCV agent candidate substance, and a method of producing a HCV vaccine. The HCV particle formation promoter comprises as an active ingredient a statin or a pharmaceutically acceptable salt thereof. Addition of the statin or pharmaceutically acceptable salt thereof to HCV-infected culture cells can promote formation of infectious HCV particles and enhance production of the particles. In addition, an anti-HCV agent candidate substance is evaluated by culturing HCV-infected cells in the presence of the HCV particle formation promoter and the anti-HCV agent candidate substance. Further, a HCV vaccine is produced by using HCV particles produced by the method of enhancing production of HCV particles.