To provide a printer and an image processing device that can execute an operation for synthesizing an arbitrary character or a character image with a main image to be printed and executes the operation in low cost and high quality at a high speed.

When printing designation that a character is superposed in a prescribed imaged image recorded on an external recording medium 24 is to be executed, character font information relating to characters to be superposed and data (program or the like) necessary for the operation for the character interposing are recorded in the external recording medium 24 beforehand. When the external recording medium 24 is loaded to a printer, a character information interpreting section 28 and an image data correcting section 30 are formed on a work memory 26 in accordance with the data necessary for the character interposing operation. The character font information is interpreted and the character is synthesized with the image to be printed by the operations of the sections 28, 30 and the image having the superposed character is printed by a printing operation section 40.