To provide a screw nail which can achieve waterproofing without performing large-scale construction by completely closing a gap with a lower hole of a building material.

A waterproof screw nail comprises: a body 2 which consists of a shaft part 5 whose outer periphery is screw-cut and whose tip is sharp and a head part 6 continued to the rear end of the shaft part 5 and having a diameter larger than that of the shaft part 5; an impermeable waterproof layer 3 which is installed around the shaft part 5; and a release paper 4 which covers the waterproof layer 3. The waterproof layer 3 includes elastic materials 7, 8 stuck to the shaft part 5, and an adhesive agent 9 applied on the surfaces of the elastic materials 7, 8.