A portable printer contains a print controller that acquires first ID of a first character printed in advance on an instant film from a wireless tag embedded in the instant film; acquires second ID of a second character contained in image data to be printed on the instant film from a header of the image data. The print controller makes a judgment based on a print permission table and the IDs of the first and second characters as to whether an image based on the image data is permitted to be printed together on the instant film. The print controller then performs an output based on a result of the judgment. The print permission table is stored in a storage portion and indicates whether the first character and the second character are allowed to be printed on a common instant film.