PROBLEM TO BE SOLVED: To provide an antibacterial agent that is low in skin irritation and has excellent antibacterial effect on gram-positive bacteria.SOLUTION: This invention provides an antibacterial agent including a biphenyl compound represented by the formula (1) or salt thereof. In the formula, R is a group selected from the group consisting of a 1-8C straight chain or branched, saturated or unsaturated hydrocarbon group and a 6-12C straight chain or branched, saturated or unsaturated hydrocarbon group substituted with an aromatic group.