PURPOSE: To easily connect maps and constitute a data base by finding an overlap area by comparing national coordinates of a couple of map drawings with each other, deleting them from one drawing and leaving them on the other drawing, and connecting them.

CONSTITUTION: Relative positions of two drawings A and B to be connected by using a coordinate system are detected and compared. Then whether or not they overlap with each other is detected by the comparison and it is decided whether or not respective figure element data taken out of the figure B are included in an overlap area. In this decision making, elements B1-B5 are completely included in the area. Those figure elements B1-B5 are deleted. Then data begin to be taken out of the drawing A and it is decided whether each figure element data contacts a connection surface. In this decision making, figure elements A6 and A7 which partially lie across the connection surface of the drawing B are objects, and the data are deleted. At this time, data of a segment element A0 are not deleted and left as they area. Then the data of the drawings A and B are integrated to connect both the drawings A and B.