A low cost transdermal patch comprises water soluble microneedles and has good performance. A transdermal patch comprises a microneedle sheet, which comprises a plurality of water soluble microneedles, moisture permeable sheet, wherethrough water vapor passes, and a reinforcing film. The reinforcing film is adhered, by an adhesive layer having an adhesive strength less than that of an adhesive layer, onto an outer surface of the moisture permeable sheet, which is the side opposite the skin opposing surface. The reinforcing film includes a water vapor barrier sheet, which blocks the passage of water vapor through at least a first area, and a removable portion around the water vapor barrier sheet. The removable portion is configured such that it can be separated from and peeled off the water vapor barrier sheet.
