Provided is an electrostatic chuck (8) of self power supply type, which is capable of supplying power while generating power to be used by an attraction electrode (3) during processing of a substrate. The electrostatic chuck (8) attracts and holds a substrate in a substrate processing apparatus (11) that processes the substrate while generating optical energy. The electrostatic chuck (8) includes: an electrode sheet (5) including an attraction electrode (3); a metal base (1) having the electrode sheet (5) laminated on an upper surface side thereof; an internal power supply for obtaining power to be supplied to the attraction electrode (3); and a voltage boost circuit (7) for boosting voltage of the power obtained by the internal power supply. The internal power supply includes a solar cell (6), and converts the optical energy into the power during the processing of the substrate, to thereby cause the electrode sheet (5) to attract and hold the substrate.