PURPOSE: To ensure constantly unchanged and satisfactory color reproducibility for recording sheets in different colors by providing a color sensor which detects the color of a recording sheet and a calculation means which corrects an image signal to be recorded on the recording sheet based on an output signal from the color sensor.

CONSTITUTION: Primary color image data VD of RGB table color group is entered in units of frame to frame memory 10 from a source such as a TV image receiver and primary image data of a single recording unit R.G.B. is read to be supplied to a color correction circuit 12. The color correction circuit 12 subtracts recording sheet color decomposition data R0, G0, B0 from primary color image data R.G.B. to be recorded and corrects the latter. Primary color image data segments R1, G1, B1 are converted to density data segments Y, M, C of YMC table color group by a color signal conversion circuit 14. The density data segments Y.M.C. receives cloudiness correction process on an ink ribbon using a color masking circuit 16 and then the processed data segments are sent to a thermal head 18. As a result, a color image which has received correction processing on the color of a recording sheet 22 and the cloudiness of an ink ribbon is recorded on the recording sheet 22.