PURPOSE:To antibacterial base composition having improved activity, and containing N-acyl hydrolyzed peptide and an antibacterial agent. CONSTITUTION:A composition containing (A) N-acyl hydrolyzed peptide (the carbon number of the acyl group is 8-20 and the molecular weight of the hydrolyzed peptide is 200-5.000; e.g. 30% aqueous solution of N-cocoyl hydrolyzed peptide potassium salt) and (B) an antibacterial agent (e.g. salicylic acid, parabens, resorcinol, etc.) as main components. The N-acyl hydrolyzed peptide, which is an anionic surface active agent, has an activity to activate many antibacterial agents, and decreases the minimum inhibitory concentration to 1/2-1/(serveral thousands). For example, it is effective to staphylococci, Bacillus subtilis, Pseudomonas aerugionsa, etc.
