The present invention relates to a resin composition comprising a resin and apatite, wherein referring to the particulate form of said apatite present in the resin composition thus obtained, the apatite is present in a particulate form having an average diameter or average thickness (d) of not greater than 100 nm and an average aspect ratio (L/D) of not smaller than 5 as defined by the ratio of the average length (L) to said average diameter or average thickness (d).