NOVELTY - The method involves anodizing an aluminum substrate (3) using electrolytic solution containing organic acid i.e. oxalic acid. The obtained anodic oxidation aluminum substrate is anneal-treated above a boiling point of the organic acid, decomposition temperature or sublimation temperature. Thermoelectric conversion material is formed into an anodic oxide film (2). A thermoelectric conversion layer (1) is formed on the anneal-treated anodic oxidation aluminum substrate. The thermoelectric conversion layer is anneal-treated. Film-forming of the conversion material is performed.    USE - Method for manufacturing a thermoelectric conversion element that transforms heat energy into electric power. Uses include but are not limited to a hot spring heat electric power generation equipment, a power supply equipment for wristwatches, a semiconductor drive power supply equipment, a power supply equipment for small sensors, a solar power generation equipment, and a waste-heat electric power generation equipment.    ADVANTAGE - The method enables anneal-treating the thermoelectric conversion layer such that thermal expansion/heat shrink of the aluminum substrate can be suppressed by anneal-treating the anodic oxidation aluminum substrate while reducing a curvature of the aluminum substrate and crack of the thermoelectric conversion layer, so that electrical conductivity falling effect can be prevented. The method enables the organic acid to be remained on the substrate to be removed by anneal-treating the aluminum substrate after an anodizing process above the boiling point of the organic acid, the decomposition temperature, or the sublimation temperature, so that bad influence to the thermoelectric conversion layer by a thermolytic material of acid which occurs at the time of the annealing treatment of the thermoelectric conversion layer can be prevented without using inorganic acid for electrolyte solution of the anodizing process, thus preventing uncontrollable doping effect by a sulfur element and elemental phosphorus derived from sulfuric acid or phosphoric acid in the thermoelectric conversion layer arises, and hence providing the thermoelectric conversion element with high electrical conductivity and seebeck coefficient even if the thermoelectric conversion layer is anneal-treated.    DETAILED DESCRIPTION - The aluminum substrate is anneal-treated at a temperature more than 50 degree Celsius and less than less than 400 degree Celsius. An INDEPENDENT CLAIM is also included for a thermoelectric conversion element.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a thermoelectric conversion element.    Thermoelectric conversion layer (1)    Anodic oxide film (2)    Aluminum substrate (3)