A method for re-using unneeded expanded styrene and an apparatus for preparing comminuted expanded styrene that can be used as a starting material for injection molding. The expanded styrene is rendered re-usable through a first step of comminuting expanded styrene, a second step of illuminating far-infra-red light to the expanded styrene comminuted by the first step to reduce its volume, a third step of further comminuting expanded styrene, reduced in volume by the second step, to prepare a granulated material, and a fourth step of injection-molding the granulated material from the third step to prepare a regenerated article.
