A system for forming a structure on a print medium 1 includes: a print unit (print device) 10 for printing an electromagnetic wave-heat conversion layer for converting electromagnetic waves into heat, on a medium including an expansion layer that expands by heating; an expansion unit (expansion device) 20 aligned laterally with the print unit 10, for expanding the expansion layer by irradiating the medium with electromagnetic waves; and a top plate 30 covering the print unit 10 and the expansion unit 20 from above.