To provide an anti-MRSA(methicillin-resistant Staphylococcus aureus) agent on the basis of the findings that a tylosin derivative showing a certain level of sensitivity to macrolide antibiotics manifests sensitivity to MRSA, too.

The objective anti-MRSA agent includes, as an active ingredient, a 4"-substituted tylosin derivative represented by formula (I) (wherein R1 is H or hydroxy group and R2 is methoxy, methylthio, methylsulfonyl or benzoyl group).