This research does an analysis based on the travel speed investigation done targeting the pass of the national route 31 places of Hokkaido. Therefore a road condition in winter is put in the conditions that the deterioration of the road surface, or the decreases of the sight distance or road width are severe. As for the pass section whose condition such as horizontal and vertical alignment is bad, much severer driving technique is forced. It is a part of an important trunk road to make contact in the pass part between the cities. The deterioration of the running environment of the pass section in winter exerts a big influence on the exchanges among municipalities and the convenience for road users. The data on the travel speed investigation done in 31 pass sections at the national route of Hokkaido are used. The influence of the various factors such as weather, road surface, or alignment on the winter travel speed in pass section is analyzed. The difference of the travel speed between the upgrade and downgrade subsection is also analyzed. The downgrade of the pass section in winter is the section where braking and handling technique are difficult and careful driving technique is forced from the traffic safety as well.