A puncture device comprising a hollow needle, a fixing portion fixed to the hollow needle, a sheath portion covering a part/entirety of the hollow needle and including a plastically deformable elongating member, a holding portion holding the hollow needle and the sheath portion in an integrated manner, with the holding portion positioned between the tip portion of the hollow needle and the plastically deformable elongating member, a holding release mechanism that releases the holding of the holding portion between the hollow needle and the sheath portion after the hollow needle and the sheath portion puncture the living body. The sheath portion elongates and is held in an elongated condition when the holding portion moves by the holding release mechanism, or when the holding of the hollow needle using the holding portion in an integrated manner is released, and the elastic portion contracts.
