The needle assembly for transdermal administration comprises a substrate having a first surface and a second surface opposite to the first surface, and a plurality of fine needles projecting perpendicularly to the first surface. Have. The substrate has a plurality of grooves located on at least one of the first surface and the second surface. The plurality of grooves are configured to follow and deform the substrate following the shape on the surface of the living body skin so that the axis of each fine needle is displaced in a direction that coincides with the normal on the surface of the living body skin. Yes.経皮投薬用針集成体は、第１の面及び該第１の面とは反対側の第２の面を有する基板と、第１の面に対し垂直に突出する複数の微細針と、を有する。基板は、第１の面と第２の面との少なくとも一方に位置する複数の溝を有する。複数の溝は、各微細針の軸線が生体の皮膚における表面上の法線と一致する方向に変位するように、基板を生体の皮膚の表面における形状に倣って追従変形させるように構成されている。
