A lancet assembly is disclosed which eliminates the need for removing a resin cover that covers a pricking element. When a lancet structure is inserted into a lancet holder, a force is applied so as to separate a lancet cover, that encloses a distal end of a pricking element, from a lancet body so that the distal end of the pricking element which has been enclosed by the lancet cover is exposed in the lancet holder, and the opening of the lancet holder is positioned in front of the distal end of the pricking element. The lancet structure has a trigger which launches the pricking element of which the distal end is exposed, when the lancet structure is continually pushed into the lancet holder.