The present study investigated the canonical positions of four kinds of adverbial expressions (or adjuncts) in Japanese (i.e. modal, time, manner, and resultative adverbs) using a sentence plausibility judgment task measuring reaction times and error rates. Sentences with a modal adverb were processed faster in the Adverb-Subject-Object-Verb (ASOV) order than either the SAOV or SOAV order. For time adverbs, the mean reaction time for SOAV was longer than the mean reaction times for ASOV and SAOV, which did not differ significantly from each other. For manner and resultative adverbs, ASOV took longer to process than SAOV and SOAV, and the latter two orders did not show a reliable difference in reaction times. These results suggest that the canonical word order(s) is(are) ASOV for modal adverbs, ASOV and SAOV for time adverbs, and SAOV and SOAV for manner and resultative adverbs, as predicted by the following syntactic structure of Japanese. [_MP (Modal-Adv.) [_IP (Time-Adv.) Subject (Time-Adv.) [_VP (Manner/Resultative-Adv.) Object (Manner/Resultative-Adv.) Verb] Infl] Modal]