To assemble and remove formwork panels more easily by increasing mainly the strength of the formwork panels in the length direction.

At least one reinforcing core member (a square timber reinforcing member 6 and a board-like reinforcing member) is attached in parallel to and between long-sized reinforcing members 5 provided on one surface of a rectangular sheathing board 4 which are connected to both ends of two shorter members located at two ends of the board 7. Then, a reinforcing board having the same shape as that of the sheathing board 4 is laid over the sheathing board 4. At the coupling surface 1a at the end portion, linkage means (projected linking portion 8 and recessed linking portion 9) is formed for linking with an adjacent formwork panel 1.