To allow the simple and visual recognition of a state of the board thickness in a resin panel.

A front panel 2 has a base part 11 requiring for a board thickness management. The front panel 2 is disposed on the base part 11, equipped with ribs A, C extended in a predetermined direction and ribs B, D which are disposed so as to adjoin the ribs A, C and extended in approximately the same direction as the ribs A, C. The ribs A, C are formed to be the height projecting from the surface of the base part 11 when the board thickness of the base part 11 is not larger than the predetermined value.