In order to provide a thermoelectric conversion element which has a high Seebeck coefficient, a low thermal conductivity, and a high performance, even if the material system that has a low environmental load and can reduce the cost is used, the thermoelectric conversion element in which lattice points are classified into two or more kinds (A site and B site), lattices of which the kinds are different are connected to each other, the numbers of lattices of which the kinds are different are different (A site: 2, and B site: 1), and a lattice structure is configured by arranging nanoparticles or semiconductor quantum dots, includes areas of which conductivity types are different.