Electrochemical corrosion of a reflective layer provided in a scintillator panel is prevented. The cleaning belts clean the liquid discharge head by adsorbing attached liquid via contact with the liquid discharge head. A magnetic field is generated by supply a frequency signal to a coil, and the descaled object and the solvent are disposed within this magnetic field. The direction of the readout light which is deflected by the compensating track preferably intersects the axis through the common center of the compensating track and the measuring track, wherein the distance between the compensating track and said intersection corresponds to the length of the light path between the compensating track and the measuring track. The control part updates the mathematical model, and has a first update mode in which the mathematical model is updated using the output of the phase-lead compensator while the output of the integrator is provided to the driving unit.