Provided is an ester of 3-[(4-dipropylamino-butyl)(4-{[(1H-imidazole-2-ylmethyl)(1-methyl-1H-imidazole-2-y lmethyl)amino]methyl}benzyl)amino]propionic acid which is easily hydrolyzed in serum. The amine compound of the present invention is an ester compound represented by general formula (1). (In general formula (1), n is 1-4, and R1 and R2 represent an alkyl group having 1-3 carbon atoms.)