PURPOSE: To perform high speed, enlarged/reduced printing under a simple constitution by forming reflecting mirrors on the side of an aggregate made of various equilateral polyhedrons.

CONSTITUTION: Print data input via an external interface terminal 8 and an interface control part 7 is developed into dot image data of standard printing size by the action of an overall control part 1, and is stored in a memory 2. According to the designation of reduced printing, a rotational frequency higher than usual is set, and a driving part 16 is positioned at a reflecting mirror for reduced printing 18. After regular rotation is instructed, the dot image data is sequentially sent to the driving part 16. According to the designation of enlarged printing, a rotational frequency lower than usual is set. Upon the completion of positioning at a reflecting mirror for enlarged printing 17, a regular rotation is instructed, and the dot image data is sequentially sent to the driving part 16.