In the thin plate theory, shear deformation is neglected. This theory is unreliable for plates of considerable thickness in the vicinity of the point of application of load, and sandwich plates with shear rigidity which is very low compared with bending rigidity. A widely accepted theory which includes the effects of shear deformation was developed by Reissner and Mindlin. In recent years, composite materials have been widely employed as structure elements, and it is important to understand their characteristics for designing structures. Plates of composite material are characterized by strong anisotropy and low out-of-plane shear rigidity. This paper provides a convenient representation for the stiffness matrix of the finite element in order to analyze a sandwich plate with an anisotropic face plate and core. The formulation is based on the non-conforming element of Zienkiewicz and is obtained with a modified stiffness matrix in the condition in which the out-of-plane shear strain is constant in two directions within an element.