Provided are a composition for forming a thermoelectric conversion layer, the composition having excellent thermoelectric characteristics; a thermoelectric conversion element, in which the composition is used to form a thermoelectric conversion layer; and a thermoelectric power generating component. The composition for forming a thermoelectric conversion layer includes inorganic particles having an average particle size of 1.0 μm or less; a carrier transport material which satisfies at least one of the condition that the mobility is 0.001 cm2/Vs or more and the condition that the carrier density is 1×1010 cm−3 to 1×1021 cm−3 when the band gap of the inorganic particles is 1.5 eV or less; and a material for a thermal excitation source which is an organic material satisfying the condition that the band gap is 1.5 eV or less when the band gap of the inorganic particles is more than 1.5 eV.