Prosodic phrasing plays a crucial role in sentence comprehension because it helps listeners resolve structural ambiguities. However, explicit prosody is not available in reading. According to the Implicit Prosody Hypothesis, readers are assumed to assign default prosody to sentences, which then guides parsing decisions (Fodor, 2002a, 2002b). This study tested this hypothesis by manipulating the lexical accent of phrases, which affects the prosodic phrasing of sentences in Japanese. The results of a self-paced silent reading experiment showed faster reading times for the structure that matched the prosodic phrasing than the structure that did not. This finding suggests that readers implicitly represent a prosodic structure that plays a functional role in syntactic processing.