In districts of Japan and other Asian countries where roads are not well developed, densely mixed automobile - bicycle traffic on old narrow roads is usual. According to Japanese statistics 1980, the number o£ fatalities in traffic accidents between bicycles and automobiles surpasses 10 percent of the total and certain measures to decrease this count are requested.In the present report, the authors paid attention to automobiles approaching bicycles from behind and passing by. At first, actual traffic states on narrow roads were recorded by VTR and many dangerous scenes were observed. Then simulative experiments were performed as follows; A narrow road was set with various obstacles e.g. power pole on one side. Several types of bicycles were operated there by subjects under various conditions e.g. passing automobile on the other side.It was found that the bicycle rider was subject to physiological and psychological pressures by the restrictions from both sides and was forced to run wobbly. Therefore automobile drivers should recognize these dangerous facts and operate automobiles carefully and it is needless to say that it is necessary to improve the road conditions.