A puncture needle cartridge (4) is provided with a lancet body (5) and a lancet case (6). The lancet body (5) has a puncture needle (10)； a connector (7) that is provided on a second end side and is connected to puncture instrument (1)； a puncture needle cover (8) that covers the tip portion of the puncture needle (10) before use； a breakable component (9) that is broken when performing puncturing, thereby separating the puncture needle cover (8) and exposing the tip portion of the puncture needle (10)； guide protrusions (12) that are provided to the outer peripheral face of the puncture needle cover (8) on a first end side of the breakable component (9)； and sliding protrusions (13) that are provided closer to the second end side than the breakable component (9). The lancet case (6) has a spiral guide (14) that imparts to the lancet case (6) a rotational force acting in a specific direction when there is relative movement in the puncture direction in a state in which the guide protrusions (12) are engaged； and a sliding groove (15) that guides movement in the puncture direction in a state in which the sliding protrusions (13) are engaged. The lancet case (6) is mounted to the outer periphery of the middle section of the lancet body (5) in a state in which the breakable component (9) has not been broken. The puncture needle cover (8) further has stoppers (33) that restrict the sliding of the lancet case (6) to the second end side from a state in which the lancet case (6) is mounted to the middle section.
