This study attempts to clarify the actual road traffic circumstances and to investigate the change of accessibility of Nagano Prefecture from 1990 to1997 by using GIS. The main findings are summarized as follows. Firstly, there is a great difference between the speed of automobiles moving in the city and those moving outside the city. Secondly, as a result of extension of highway, time distance from Matsumoto to Hokushin area is reduced largely. Then, movement efficiency of automobile in Nagano Prefecture has improved, and the time required for the movement by 1km is improved from 1.3 minute to 1.0 minute.
