Better thermoelectric characteristics of a thermoelectric material containing nanoparticles are achieved. The thermoelectric material contains a plurality of nanoparticles distributed in a mixture of a first material having a band gap and a second material different from the first material. The first material contains Si and Ge. A concentration of atoms of the second material and a composition ratio of Si to Ge satisfy relational expressions in expressions (1) and (2) below with c representing a concentration of atoms (unit of atomic %) of the second material in the thermoelectric material and r representing the composition ratio of Si to Ge: r≤0.62c−0.25  (1) r≥0.05c−0.06  (2).