A puncture needle cartridge includes a puncture needle holder configured to be cylindrical, placed on an outer circumferential surface of a lancet body, and provided with an opening through which a puncture needle is allowed to protrude, and a protective cap adapted to cover and protect the opening and configured to be separable from the puncture needle holder. The protective cap includes a base adapted to cover the opening when the protective cap is joined and a pair of raised walls which protrude from the base toward the puncture needle holder and whose tip portions are placed facing each other. Tip portions of the raised walls pinch the puncture needle holder by spreading against elastic deformation when the protective cap is joined to the puncture needle holder, and when the protective cap is separated from the puncture needle holder, a space between the tip portions becomes smaller than outside diameter of the puncture needle holder due to elastic deformation.
