The present invention verifies a method of reducing skin irritation (particularly, cumulative skin irritation) caused by transdermal administration of a local anesthetic using iontophoresis, and provides an electrode pad for relief from a puncture pain which is safe not only at single administration but also at repeated administrations. The electrode pad comprises a base sheet (1)； an electrode (3) placed on the base sheet (1)； an adhesive sheet (2) placed on the base sheet (1) and having an opening (2a), within which the electrode (3) is exposed； and a medicament reservoir (4) containing a local anesthetic and placed in the opening (2a) of the adhesive sheet (2) while being in contact with the electrode (3). A predetermined space (r) is provided between an inner peripheral surface of the opening (2a) of the adhesive sheet (2) and an outer peripheral surface of the medicament reservoir (4), and a thickness of the adhesive sheet (2) and a thickness of the medicament reservoir (4) are substantially equal to each other. Alternatively, the medicament reservoir (4) has a non-hemispherical convex dome shape having a maximum height which is greater than a thickness of the adhesive sheet (2).
