Abstract: A method for producing a digital topographic map, comprising the following steps of: a step for dividing a basic map, which is produced through UTM drawing method, into grid-like sectors at a predetermined distance, and further dividing the sector obtained into a smaller one (4), thereby producing small sectors while interpolating discontinuous data being in short between each sectors and within each of the sectors; a step for producing digital data by relating x,y coordinates of the small sector (4) obtained and a sea level obtained through measurement, upon basis of an algorithm having a rationality, and connecting the small sectors (4) being same in the sea level thereof with a straight line, thereby producing a first topographic map (5), on which contour lines (6) are formed with lines of segments; and a step for conducting a smoothing process upon the contour lines (6) of said first topographic map (5), mathematically, thereby producing a second topographic map (7), on which the contour lines (6) are for