Sixteen Japanese learners among native English readers and twenty-four native Japanese readers made lexical classification to Hiragana or Katakana written Japanese words and foreign loan words. A Stroop-like effect was shown in foreign loan word but not in Japanese word condition among foreign Japanese learners, whereas a Stroop-like effect was shown in both Japanese and foreign loan word condition among native Japanese readers. Based upon these results, lexical representations of the native Japanese readers and foreign Japanese learners for the foreign loan words were discussed.