A multidentate ligand includes at least two planar tetradentate coordination sites in one plane, each of the planar tetradentate coordination sites containing four nitrogen-containing groups of at least one of imino, amido and amino groups, and has the nitrogen atoms of the four nitrogen-containing groups as coordinating atoms in one plane. A metal complex assembly has one of two-dimensional and three-dimensional structures and contains metal complex chains and electroconductive wires, the metal complex chains each contain assembled metal complexes, the electroconductive wires each contain molecules serving as at least one of an acceptor and a donor, and the metal complex chains intersect with the electroconductive wires at such positions that the metal complexes and the molecules serving as at least one of an acceptor and a donor are capable of interacting with each other.