The purpose of the present invention is to provide a novel tissue regeneration accelerator and tissue regeneration method. The present invention relates to: a composition for accelerating tissue regeneration, accelerating cell differentiation and/or accelerating cell multiplication comprising a component selected from the group consisting of activated stellate cells, the decomposition product of activated stellate cells, MMP14, collagen that has been treated with MMP14, and the secretion product of activated stellate cells; a composition for suppressing cell multiplication comprising MMP14 suppressing material; and a cell cultivation substrate comprising collagen that has been treated with MMP14.