Vehicular back door having antitheft structure

A vehicular back door (20) has an antitheft structure (13) for preventing illicit unlocking of a latch mechanism (40) provided on the back door for keeping the back door in a closed position. The antitheft structure includes a shield wall (60) disposed to cover at least one side of the latch mechanism in a width direction of the vehicle and connected with an outer panel (21) and a sidewall section (33) of an inner panel (31), and a bead (37) formed on the door facing section of the inner panel and projecting into an internal space (Sp) of the back door toward the outer panel, the bead being located adjacent to the shield wall.