Provided is a puncturing tool with which an internal needle can be accommodated within an internal needle hub or the like through an operation to draw in the internal needle, and which can block the passage hole through which the needle is inserted and prevent the internal needle from protruding to the outside, accomplishing this without employing restoring force of a needle clamp member. The tool is provided with an outer barrel (6) attached in retractable fashion inside an internal needle hub (41), and an inner barrel (7) attached in retractable fashion inside the outer barrel (6), and having a passage hole (73) for insertion of an internal needle (3). The inner barrel is further provided with passage hole blocking means (a space part (75), a block body (74)) which moves at least a portion of the passage hole, from a position at which the internal needle (3) may be inserted therein to a position at which the internal needle (3) cannot be inserted, and blocks the open state of the passage hole (73). Insertion of the internal needle (3) is blocked by the passage hole blocking means.
