A medical adhesive patch, includes: a support film including a barrier layer which contains a water-soluble polymer compound and montmorillonite, and which is laminated on one surface of a support including polyurethane an adhesive layer which contains a medicine and a plasticizer, and which is laminated on a barrier layer of the support film, the medical adhesive patch has a percentage content of montmorillonite in the barrier layer is equal to or more than 2 percent by weight and equal to or less than 22 percent by weight.
