According to Biederman and Tsao (1979), ideographic script yields more interference than phonetic script in Stroop color-naming task. They attributed this effect to the fundamental differences in the perceptual demands in reading these scripts. In order to examine this hypothesis two experiments using Kanji and Kana were conducted, in which the semantic relationship between the distractor word and the color was manipulated. It was expected that if the above hypothesis was correct the script type effect would not be influenced by the semantic attributes of distractor words. In experiment 1 using verbal response (subjects were 30 undergraduates), although the script type effect was not shown in any semantic relationship conditions, the influence of the meaning of distractor words on the interference score was observed (semantic category effect). In experiment 2 using manual response (subjects were 24 undergraduates), both the semantic category effect and the script type effect were observed, and the latter was found to vary as a function of semantic relationship between the distractor words and the colors. These results are interpreted as evidence indicating that the script type effect on Stroop interference takes place at the semantic processing level.