An antibacterial agent having high antibacterial activity against Mycobacterium avium subsp. paratuberculosis is provided. Specifically, the antibacterial agent of the present invention having high antibacterial activity against Mycobacterium avium subsp. paratuberculosis is a caprazamycin derivative represented, for example, by the following general formula (II): wherein Me is a methyl group; and R1 is a straight or substantially straight chain alkyl group having 5 to 21 carbon atoms, a straight or substantially straight chain alkenyl group having 5 to 21 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, or a phenyl group substituted at the para-position with a straight chain alkyl group having 1 to 14 carbon atoms, a straight chain alkoxy group having 1 to 9 carbon atoms or a cycloalkyl group having 5 to 12 carbon atoms.