Compared to studies on prosodic effects on the comprehension of syntactic ambiguity in English, there are relatively few that investigated prosodic effects in East-Asian languages. This study examined the role of prosodic information in processing syntactically ambiguous sentences in Japanese. For syntactically ambiguous sentences containing relative clauses, this paper investigated whether prosodic information is immediately available during the process of these ambiguous sentences. Results from an auditory comprehension experiment with an on-line, cross-modal naming task seemingly suggest that contrary to the findings from the off-line study that examined the same constructions, prosodic information may not be immediately available to Japanese listeners. A possible account for failure to obtain effects of prosodic information is provided.