The processing apparatus includes: a first storage device that stores correction image information defining a correction image Ap formed on the surface of a to-be-processed medium S, in which the positional relationship relative to an output image formed on the surface of the to-be-processed medium S is known; a second storage device that stores processing area information defining an area of the surface of the to-be-processed medium S heated by a heating unit, in which the positional relationship with the output image formed on the surface of the to-be-processed medium S is known; and a control unit that uses a detection result of a correction image formed on the surface of the to-be-processed medium S detected by an image detection unit and the correction image information to correct a heating position on the surface of the to-be-processed medium S heated by the heating unit indicated by the processing area information.