When the patch (12) being stuck to the skin the gel for the donor where the medicine is enclosed (30) with, the gel for reference (34) with, the gel for the donor (30) the 1st electrode which is connected (38) and the gel for reference (34) the 2nd electrode which is connected (40) with the patch which it has (12) with in the dermal medicine dosage device which it possesses, as at specified period direct current the 1st electrode (38) and the 2nd electrode (40) is supplied between, in the period when direct current is not supplied alternating current1 electrodes (38) and the 2nd electrode (40) supplying between, it calculates capacitance, the patch (12) it judges sticking state on the basis of the capacitance which was calculated.薬剤が封入されたドナー用ゲル(30)と、リファレンス用ゲル(34)と、ドナー用ゲル(30)に接続された第1電極(38)及びリファレンス用ゲル(34)に接続された第2電極(40)とを備えるパッチ(12)とを有する経皮的薬物投与装置において、パッチ(12)が皮膚に貼付されているときに、所定の周期で直流電流を第1電極(38)及び第2電極(40)間に供給するとともに、直流電流が供給されていない期間に交流電流を第1電極(38)及び第2電極(40)間に供給してキャパシタンスを求め、求めたキャパシタンスに基づいてパッチ(12)の貼付状態を判断する。
