A method of manufacturing an core product includes heating the resin pellet at a temperature higher than 25° C. for 24 hours or longer, the resin pellet being formed of a thermosetting resin composition including epoxy resin, a curing agent, accelerator, and a release agent. The method includes holding a core body having a resin formation region, which is a region in which a resin is to be formed by injection of a melted resin, between a pair of holding members, and disposing the heated resin pellet in a resin pot formed in at least one of the pair of holding members. Additionally, the method includes melting the resin pellet in the resin pot and injecting the melted resin into the resin formation region through a resin channel extending from the resin pot in communication with the resin formation region, and curing the melted resin injected into the resin formation region.