The disclosed substance-supplying device supplies substances such as pharmaceuticals to a living body through fine needles, and facilitates supplemental supplying of the substance and successive supplying of different types of substances. A plug (14) that encapsulates a medicinal solution within a medicinal solution chamber (32) can be installed and removed from a container body (12). The plug fits movably with the container body and by pushing the plug in, a sealing membrane (30) that seals the medicinal solution within the plug contacts membrane-rupturing protrusions (40), rupturing the sealing membrane. As a result, the medicinal solution flows out from the medicinal solution chamber, and is supplied to the living body transdermally through the through-holes (38) of the fine needles (36). If the medicinal solution must be supplemented or exchanged, the plug (14) is removed and exchanged with a new plug (14).
