A thermoelectric conversion element, comprising: a first electrode; a second electrode; and a thermoelectric conversion layer (2, 51), a first intermediate layer; and a second intermediate layer; wherein the first intermediate layer is provided between the thermoelectric conversion layer (2, 51) and the first electrode; the first intermediate layer is in contact with the thermoelectric conversion layer (2, 51); the first electrode is in contact with the first intermediate layer; the second intermediate layer is provided between the thermoelectric conversion layer and the second electrode; the second intermediate layer is in contact with the thermoelectric conversion layer (2, 51); the second electrode is in contact with the second intermediate layer; the first electrode and the second electrode are composed of a CuZn alloy; the thermoelectric conversion layer (2, 51) is composed of a thermoelectric conversion material containing Mg; the thermoelectric conversion material contains at least one kind of element selected from the group consisting of Sb and Bi; the thermoelectric conversion material contains at least one kind of element selected from the group consisting of Se and Te; the thermoelectric conversion material has a La 2 O 3 -type crystalline structure; a composition of the first intermediate layer is different from both a composition of the first electrode and a composition of the thermoelectric conversion layer (2, 51); and a composition of the second intermediate layer is different from both a composition of the second electrode and a composition of the thermoelectric conversion layer (2, 51). a first electrode; a second electrode; and a thermoelectric conversion layer (2, 51), a first intermediate layer; and a second intermediate layer; wherein the first intermediate layer is provided between the thermoelectric conversion layer (2, 51) and the first electrode; the first intermediate layer is in contact with the thermoelectric conversion layer (2, 51); the first electrode is in contact with the first intermediate layer; the second intermediate layer is provided between the thermoelectric conversion layer and the second electrode; the second intermediate layer is in contact with the thermoelectric conversion layer (2, 51); the second electrode is in contact with the second intermediate layer; the first electrode and the second electrode are composed of a CuZn alloy; the thermoelectric conversion layer (2, 51) is composed of a thermoelectric conversion material containing Mg; the thermoelectric conversion material contains at least one kind of element selected from the group consisting of Sb and Bi; the thermoelectric conversion material contains at least one kind of element selected from the group consisting of Se and Te; the thermoelectric conversion material has a La 2 O 3 -type crystalline structure; a composition of the first intermediate layer is different from both a composition of the first electrode and a composition of the thermoelectric conversion layer (2, 51); and a composition of the second intermediate layer is different from both a composition of the second electrode and a composition of the thermoelectric conversion layer (2, 51).