PURPOSE: To attain the gradation recording with high accuracy by dividing each heating element of a thermal head into an even number and an odd number columns, and driving in time division each column with a time difference so as not to give affect on heating elements of other column from a heating element of one column, thereby applying gradation recording by area modulation.

CONSTITUTION: A recording data DATA transferred serially from an external host machine is shared into a data of an even number bit and a data of an odd number bit and one bit of white picture information is inserted respectively between shared bits to form each data of the even number and the odd number column having a capacity for each one line's share, then the even number column data is latched, the 1st recording pulse signal PS if fed to a thermal head 4 to drive each heating element of the even number order in response only to the data of the even number order bit, then the odd number column data is latched, and the 2nd recording pulse signal PS is fed to the thermal head to drive each heating element of the odd number order in response only to the odd number bit data by the control means.