It is the purpose of this paper to evaluate accuracy of large-scale Ino Maps （Dai-zu） of 1 to 36000. Ino surveyed coastlines and main roads in almost whole Japanese Islands by the method Dosen-ho, a kind of open traverse surveying. This author traced polygonal lines of the coasts and roads in the maps and checked latitudes and longitudes of the points of the lines comparing with the modern map of Geographical Survey Institute（Geographical Information Authority nowadays）.
The difference of geographical positions in the two maps shows for him how to correct results of surface surveying on the basis of astronomical observations. It is verified in his process of making maps that the accuracy of the Dai-zu and how he corrected the results of surface surveying with the latitudes astronomically observed. Although there are some errors of the map projection for the small scaled maps, the Dai-zu in 1/36000 is fairly fine in consideration of his poor survey instruments and survey methods.
