A drug delivery device comprising a needle retractable (1), a proximal end and a distal end that is, (5), the first to be located on an external surface (4), an outer surface an inner surface which form channels (6) I include the convex portion of the (7). [Selection Figure Figure 3後退可能な針(1)を含む薬物送達デバイスであって、その遠位端及び近位端が、チャンネル(6)を形成する内面(4)、外面(5)、外面上に位置する第一の凸部(7)を含む。【選択図】 図3