<;P>;PROBLEM TO BE SOLVED: To discover a new pharmacological active ingredient contained in royal jelly. <;P>;SOLUTION: At least one kind selected from adenosine, adenosine N1-oxide, adenosine-5'-monophosphate (5'AMP), adenosine-5'-monophosphate-N1-oxide (AMP N1-oxide), nicotinamide adenine dinucleotide (NAD<;SP>;+<;/SP>;) and nicotinamide adenine dinucleotide-N1-oxide (NAD<;SP>;+<;/SP>;N1-oxide) contained in an aqueous extract of the royal jelly fractionated to a molecular weight of &le;2,000 is used as an active ingredient for a human osteoblast proliferation inhibitor. <;P>;COPYRIGHT: (C)2011,JPO&INPIT