A thermoelectric conversion layer contains carbon nanotubes and a surfactant, and in an upper portion and a lower portion and/or a side face end surface and a center, a mass ratio obtained by dividing the carbon nanotubes by the surfactant is higher in the upper portion and/or the end surface than in the other portions. A layer which contains carbon nanotubes and a surfactant and will become a thermoelectric conversion element is formed, the layer is washed with a washing agent which dissolves the surfactant but does not dissolve the carbon nanotubes. Accordingly, provided is a thermoelectric conversion element and a thermoelectric conversion module, each having not only high adhesiveness between the substrate and the thermoelectric conversion layer but also excellent thermoelectric conversion performance; and methods for manufacturing the thermoelectric conversion element and the thermoelectric conversion module.