The purpose of this work is to measure discomfort of driver and bicycle when they pass roadway simultaneously and make few suggestions for composition of bicycle lane. First, we researched mental barrier for bicycle users when they pass roadways by questionnaires and counting of passing position of bicycle. Second, we conducted experiments by means of driving simulator to measure driver’s mental load. We also made eye measurements of side interval between actual car and bicycle. We found cars and bicycles feel discomfort when side interval is less than 1.5m. This discomfort disappeared when side interval was more than 2.5m.