Abstract: An apparatus comprises a carrier including a permanent electromagnet and configured to hold a mask containing a magnetic material and a substrate by magnetically attracting the mask via the substrate, and a sensor unit configured to sense a state of the carrier using a magnetic sensor for sensing a magnetic field from the permanent electromagnet, the permanent electromagnet including a variable-polarity magnet, a coil which generates a magnetic field for changing the polarity of the variable-polarity magnet, and a fixed-polarity magnet having fixed polarity, a state of the carrier is set in one of a first state in which the mask and the substrate are held by a magnetic field generated by the variable-polarity magnet and the fixed-polarity magnet, and a second state in which the mask and the substrate are not held, by controlling the polarity of the variable-polarity magnet by the magnetic field generated by the coil.