To provide a reinforcing plate sticking device of an outer wall panel capable of enhancing working efficiency, contriving reduction of a labor cost, shortening time required for manufacture of the outer wall panel and further preventing damage of the outer wall panel during working by automating sticking work for a reinforcing plate on the outer wall panel.

The reinforcing plate sticking device has a transport mechanism 2 for horizontally transporting the outer wall panel 3, a reinforcing plate supply mechanism 8 for supplying a band-like reinforcing plate 7 wound around a rotatably supported winding roller 6 frontward, a sticking mechanism 11 vertically operating a suction part 10 sucking a front end 9 of the reinforcing plate 7 and sticking the front end 9 of the reinforcing plate 7 on a lower face of the outer wall panel 3, a pressure-fitting mechanism 13 pushing the whole reinforcing plate 7 sticking the front end 9 by the sticking mechanism 11 to be adhered to the outer wall panel 3.