A disposable lancing device including: a housing; a spring member; a lancet having a skin puncture needle, the spring member and the lancet being housed within the housing such that a needle tip of the skin puncture needle is adapted to be projected out from the housing under urging of the lancet by the spring member to perform skin puncture procedure; and a protective cap having a needle passage hole and covering the needle tip of the skin puncture needle, the protective cap being adapted to separate from the skin puncture needle and rotate so that the needle passage hole of the protective cap is positioned on a path of projection of the skin puncture needle, and the skin puncture procedure is performed with the protective cap supported on the housing.