Optimal lamination structure is obtained for laminated plates with simply supported or clamped edges under compressive loads. First, bending-extension coupling is shown to reduce buckling load of laminated plates, and symmetric laminated plates are found to be better than unsymmetric ones from the point of optimization. Next, optimal lamination of symmetric laminated plates is examined by introducing invariants of stiffnesses and two lamination parameters α, β. It is shown that optimal lamination exists in angle-ply laminates for simply supported plates and in either angle-ply or crossply laminates for clamped ones.