PURPOSE: To provide the paint-out plotting method for polygon capable of making high-speed of plotting time without using a special device for plotting.

CONSTITUTION: In the paint-out plotting method for polygon performing the plotting of polygon by painting out the pixel corresponding to the graphic pattern on the display screen with plural pixels arranged, the polygon for plotting is divided along one direction of the display screen and position data on the boundary of the polygon obtained by the division are obtained. In the same division in one direction, a group of position data is formed (S1) by two position data holding between the polygon inside. By making a dot on the pixel which is held between by the group of position data (S3). Thus the plotting of polygon is performed, thus painting-out of polygon is made.