PURPOSE: To obtain a lightweight FRP plate generating no lowering in rigidity without using an expensive carbon fiber by unifying a surface material part composed of a resin reinforced by a fiber reinforcing material with a lattice composed of the resin present on one surface of the surface material part and reinforced by unidirectional fiber reinforcing materials crossing each other.

CONSTITUTION: A plate-shaped molded article made of FRP has constitution such that an FRP lattice 3 is integrally provided to the single surface of a surface material 2 being an FRP flat plate. The FRP flat plate part and the FRP lattice part are integrally formed to form an integrated molded article as a whole. The FRP lattice part 3 is constituted of a combination of crosspieces made of FRP reinforced by unidirectional fiber reinforcing materials, that is, a combination wherein crosspieces are allowed to cross each other at least in two directions, usually, two longitudinal and lateral directions. The unidirectional fiber reinforcing materials also cross each other at the intersecting parts of said crosspieces. The pitch between the crosspieces is pref. 50-150mm.