PURPOSE:To execute an anti-aliasing processing at high speed. CONSTITUTION:A CPU 202 calculates the starting (x) coordinate value of a left edge part to be drawn, the starting (x) coordinate value of a right edge part to be drawn, the range of the left edge part to be drawn and the range of the right edge part to be drawn, and a linear drawing device 206 decides the approximate area rate of respective edge part picture elements with the density value of a graphic to be drawn, a (y) coordinate value to be drawn, the starting (x) coordinate value of the left edge to be drawn, the starting (x) coordinate of the right edge part to be drawn, the range of the left edge part to be drawn and the range of the right edge part to be drawn as input parameters and executes linear drawing in the (x) axis direction of a designated line.