PURPOSE: To reduce the cost by decreasing a memory capacity to 1/3 and to shorten the printing time by concurrently conducting the printing operation and a communication in a color printer for a personal computer.

CONSTITUTION: The image data memory in a printer is provided only for one color, and the memory area of a memory 202 is repeatedly used at each color printing. In this case, the image data of next color is received from a host computer 210 and stored in the memory 202 while conducting the printing operation of a printing unit 204. At this time, in order not to damage the color data during printing at present when the received data is stored in the memory 202, the pointer 101 for indicating the place of the print-finished color data of printing at present and the memory address in the case of storing the received data in the memory 202 are managed, and the data is printed while controlling the communication so that the memory address does not pass the pointer 101.