This study examines the activities relating to the carcinogenicity of six types of benzophenone derivatives (benzophenone, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone and 2,2'-dihydroxy-4,4'-dimethoxybenzophenone) currently used in plastic products as additives to serve as ultraviolet absorbing agents. The evaluation of the initiation activity used a light absorption umu-test, a luminescent umu-test and the Ames test. The promotion activity was examined by a Bhas assay, a method that uses Bhas 42 cells for the formation of transformation foci. The luminescent umu-test indicated positive initiation activity of 2-hydroxy-4-methoxybenzophenone, and pseudo-positive activity of 2,4-dihydroxybenzophenone and 2,2'-dihydroxy-4-methoxybenzophenone. In the Ames test, 2-hydroxy-4-octyloxybenzophenone showed pseudo-positive initiation activity. Conversely, 2,4-dihydroxybenzophenone indicated weak promotion activity at 10 microg/ml concentration.