This study is intended to examine differences of dictionary use between literary reading mode and expository reading mode in a foreign language. These two reading modes are defined based on a Transaction Model. This study, which examined 30 Japanese learners of English, yielded the following three points as main findings: (1) under a literary reading condition, they used a dictionary most to see whether known words had a different meaning that they did not know; (2) under an expository reading condition, they tended to use a dictionary for checking the meaning of new words and did not devote attention to the other meanings of known words; and (3) dictionaries were used for only limited purposes in both reading modes.