It is intended to provide a novel amino acid organic compound which can be used as a labeling precursor compound for radioactive halogen-labeled amino acid compounds including [ 18 F]FACBC, and which prevents methanol from remaining in the radioactive halogen-labeled amino acid compounds produced therefrom. The novel amino acid organic compound is a compound represented by the following formula: wherein n is an integer of 0 or of 1 to 4； R 1 is an ethyl, 1-propyl or isopropyl substituent； X is a halogen substituent or a group represented by -OR 2 ； R 2 is a straight-chain or branched-chain haloalkylsulfonic acid substituent with one to 10 carbon atoms, trialkylstannyl substituent with 3 to 12 carbon atoms, fluorosulfonic acid substituent or aromatic sulfonic acid substituent； and R 3 is a protective group.
