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 [18F]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; R1 is an ethyl, 1-propyl or isopropyl substituent; X is a halogen substituent or a group represented by —OR2; R2 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 R3 is a protective group.