To obtain an inexpensive form panel for corners, by mutually butting the respective front ends of two foamed plastic panels diagonally cut at the end face thereof and sticking a reinforcing sheet on the butted face.

The mutual front ends of cut faces 12a, 12b are arranged to mutually butt two foamed plastic panels 11a, 11b diagonally cut at the end faces so that the cut faces 12a, 12b are oppositely positioned. And in this state, a reinforcing sheet 13 is stuck on a face different from the cut faces 12a, 12b of the butted part and the two panels are integrally unified. In this way, a form panel 10 for corners which can be sufficiently adapted for as a corner form for a relatively low placing concrete that a high waterproofness is not required, can be produced in a low cost.