A wire-grid metal sheet includes a grid portion defined by a plurality of spaced strip-shaped longitudinal members extending longitudinally and cross members extending substantially perpendicular to the longitudinal members. A wire grid is made by attaching the wire-grid metal sheet to a frame. The cross members are arranged at intervals at least about five times greater than those of the longitudinal members. The longitudinal members and the cross members may define a lattice pattern. Alternatively, the longitudinal members or the cross members may be arranged in a staggered manner.