A 3d-4f complex with the formula of {Na[(CuL)(4)Gd]}(1 infinity) was prepared, where (CuL)(-) is a "ligand-complex," [N-(4-methyl-6-oxo-3-azahept-4-enyl)oxamato]copper(II). The structure consists of a pin-wheel-like CU4Gd core and Na+ ion as a connector to give a one-dimensional chain. The magnetic data and their analyses demonstrated an intramolecular ferromagnetic interaction within a CU4Gd core and an intercore antiferromagnetic interaction operating through Na+ ion with the coupling parameters of J = +1.09cm(-1), zJ' = -0.07 cm(-1); S-Cu = 1/2, S-Gd = 7/2).