The present invention provides an adhesive patch for the treatment of tinea unguium intended to be applied once a day, comprising terbinafine and/or a pharmacologically acceptable salt thereof in an amount of 3 mg/cm2, wherein the adhesive patch is used so that the terbinafine concentration in nails may be 295±127 ng/mg and the terbinafine concentration in plasma may be 23 pg/mL or less, 8 weeks after the start of application, per cm2 of the patch size.