PURPOSE: To enable printing of such a large print as poster by winding a material to be printed around a cylinder and by devising to rotate the cylinder so as to allow printing head to move in a single direction with respect to the sheet.

CONSTITUTION: There is drum means 14 forming cylindrical surface S to support sheet material to be printed, and the drum is rotated by motor M and driving belt 18. The drum is equipped with at least two wheel assemblies 22 with spokes at ends of the wheel, and cylindrical outer shell 25 has corrugated metal shell 27 useful for supporting the wheel assemblies 22 with 3 spokes on supporting shaft 16 at a relative position shifted along the axis. Action of ink jet printing head and rotation of the drum means are controlled by computer aided controller 32. Printing part 30 has been mounted on supporting carriage 31 so as to move horizontally on supporting rail 29 in parallel to central axis of the drum, and carriage driving motor 33 has been controlled by control unit 32.