PROBLEM TO BE SOLVED: To increase operability of a puncture instrument which for example, punctures a needle to a human body and makes blood flow out to measure blood glucose level.SOLUTION: In a front end of a lancet holder 28, a holding piece 45 opened to the outer peripheral direction is provided. In a holder insertion cylinder 25, a sheltering hole 46 for retracting the holding piece 45 of the lancet holder 28 in the outer peripheral direction is provided. In the rear side of the sheltering hole 46, a restraining part 47 for restraining the movement of the holding piece 45 in the outer peripheral direction is provided.
