PURPOSE: To form a dot having a gradation of concentration, by applying the voltage corresponding to the change of density of the picture element of an original picture between a recording electrode and a return circuit electrode for a prescribed period of time and fusing the part of an ink sheet to transfer the fused part to a recording medium.

CONSTITUTION: An ink sheet 1 is made to touch a recording medium 2, and a recording electrode 3 and a return circuit electrode 5 set with a cerrain space to the electrode 3 are made to touch the sheet 1. The image signal voltage 6 which is transformed almost in correspondence to the change of concentration of the picture element of an original picture is applied between the electrodes 3 and 5 for a prescribed period of time. Thus the sheet 1 is fused at the part near the electrode 3, and this fused area is shifted to the medium 2. In such way, a dot having the concentration nearly corresponding to the concentration of the picture element of the original picture is formed to the medium 2.