To obtain the guidance of plants sensitivity or resistance to $SO_2$ gas, 16 species, 25 varieties of plants were exposed to 0, 0.2, 0.4, 0.7 and 1.5 ppm of $SO_2$ gas in controlled environmental chamber and the visible injury on the plants was observed. Plant sensitivity and/or resistance rankings at each guidance appeared different, based on first injured time, injury degree, and injury index. Only 10 varieties of plant are equal in the ranking at different base. It is concluded that recommended guidance for sensitivity and resistance of plants to $SO_2$ gas are the first injured time and the injury degree, respectively.