The object is to provide a promoting agent for bone formation, a therapeutic method for bone formation and a process for preparing a promoting agent for bone formation. A promoting agent for bone formation which comprises at least one of kistrin, echstatin, a peptide or polypeptide containing the amino acid sequence ArgGlyAsp in the molecule such as a peptide represented by Gly-Arg-Gly-Asp-Ser or a compound represented by the following general formula (IX) and so on, as well as a biologically acceptable salt thereof wherein R16 represents —N(R20)2 (R20 represents a hydrogen atom or a C1-C4 alkyl group), R17 represents a hydrogen atom or a C1-C4 alkyl group, R18 represents a hydrogen atom, a C1-C4 alkyl group and so on, R19 represents OH, NH2 and so on, Y represents —NH—, —O— or a direct bond, a represents 1-3, b represents 1 or 2, c represents 0 or 1 and d represents 0 or 1.