A power generator for taking out electric power from a pyroelectric part by changing temperature of the pyroelectric part exhibiting a pyroelectric effect is disclosed. The power generator includes a heating section that heats the pyroelectric part using a heating medium; a cooling section that cools the pyroelectric part using a cooling medium; and a thermal resistance changer that changes at least one of thermal resistance between the heating medium and the pyroelectric part and thermal resistance between the cooling medium and the pyroelectric part.
