Plates are frequently used in constructing nuclear power plant structures as a structural member. Creating holes in plates, complying with the function, may sometimes is needed. As the buckling may cause the plate to be failed, this study deals with investigating the effects of the thickness of the plate having through holes on its buckling. A range of thicknesses from 1mm to 10mm is considered for the plate to be investigated. Two holes of diameters of 10mm are created in the plate. The load having the magnitude of 1N/m is applied on the left edge of the plate. Both plates with and without holes are investigated. Results showed that thin plates can fail due to geometrical failure while thick plates may fail due to materials failure. The maximum difference in buckling load between the plate with hole and without hole has occurred for the plate having the thickness of 6mm.