The power supply apparatus includes a power supply unit, a piezoelectric element for transferring heat of the power supply unit to a floor panel, and an element power supply control circuit for controlling application of a voltage to the piezoelectric element. The piezoelectric element is placed between the power supply unit and the floor panel and is switched between a contact state in which the piezoelectric element is in contact with the power supply unit and the floor panel and a non-contact state in which the piezoelectric element is not in contact with the power supply unit and/or the floor panel in accordance with the application of a voltage.