An object of the invention is to provide a bone filling material capable of promoting the bone regeneration effect of a growth factor such as platelet rich plasma (PRP).Inventors of the invention anticipated that the bone filling material adsorbs a growth factor like PRP, and the combined use of the bone filling material with PRP, the bone regeneration effect of PRP might be impaired. Further, the invention is basically related to the inhibition of this adsorbing effect of the bone filling material by using a capping agent. Since the adsorbing effect of the bone filling material is thus inhibited, PRP can exert the bone regeneration effect thereof in the case of using the bone filling material together with PRP.