An asphalt roof shingle sealing device comprised of a single flat non-perforated blank sheet of metal or rigid plastic, preferably aluminum or copper and having a width, length and thickness selected to substantially span the beneath the width and length of a shingle to be repaired having at least one hole, tear or puncture therein and includes a cutting edge for cutting through adhesive between shingles to be repaired and securing elements for securing the blank sheet in place beneath the shingle to be repaired thereby preventing any water passing through the hole or puncture in the shingle, or allowing any water passing through the hole or puncture to be collected by the blank sheet and drained onto a shingle below the repaired shingle.