A nailing device is adapted for sequentially driving a plurality of roofing nails (40) into a targeted framing structure, and includes a shearing unit which is actuated by a shear initiating unit to displace to a shearing position, where a leading roofing nail (40) is shorn off from the remainder of the roofing nails (40), and a trigger member (34) which is disposed synchronously activate a shot initiating unit (31) toblastastrikingrod (33) for driving the leading roofing nail (40), and the shear initiating unit, so as to enable consecutive driving of the roofing nails (40) into the targeted framing structure to thereby enabling installation of roofing shingles (8).