Nanoindentation test has been performed to characterize the mechanical properties of aluminium alloy foam cell wall. Two of the mechanical properties: hardness and Young’s modulus of cell wall material were evaluated using the stiffness of contact during both loading and unloading. Properties obtained from unloading stiffness were in better agreement with the conventional test result than those obtained from loading stiffness. The finite element analysis using nonlinear finite element code ABAQUS was performed to characterize the yield strength and the stress-strain curve of the cell wall material of the foam. Properties of foam cell wall material were found to be substantially different from the properties of the material before foaming. The methodology used in this paper can be effectively used to characterize the mechanical properties of cell wall of any cellular material.