PURPOSE: To uniformly bring a heat transfer sheet into close contact with a rigid flat platelike image receiver, to hole its flatness and to condense a uniformly condensing spot by providing means for bringing the receiver into close contact with the sheet, and scanning means for maintaining an interval between a focusing surface and a condensing lens constant.

CONSTITUTION: A position regulating mechanism 27 of a condensing lens 7 is provided at an optical head 4 to regulate the focusing position of a condensing spot 22. The mechanism 27 automatically measures a condensing path length 21, and aligns it. An image receiver 2 is disposed on an image receiver suction unit 34 in a buried state, sucked in vacuum by an image receiver suction hole 36, and the receiver 2 is held in close contact with a close contact base 32 with high flatness. A heat transfer sheet 1 is sucked in vacuum by a sheet suction hole 35, and held on the receiver 2 and the base 32 with high flatness. Since the depth of an image receiver holding groove is substantially the same as the thickness of the receiver 2, the sheet 1 is scarcely wrinkled at the edge of the receiver 2.