Near-infrared spectroscopy was used to elucidate the neural mechanisms underlying the processing of Japanese lexical pitch-accent by adult native speakers of Japanese. We measured cortical hemodynamic responses to a pitch pattern change (high-low vs. low-high) embedded in disyllabic words or pure tones. The results showed that the responses to the pitch pattern change within the words were larger than those for the pure tones in the left temporoparietal region. Activation in the left frontal region was also observed for the perception of pitch pattern change within the words. These results indicate that the left language-related regions contribute to the processing of lexical pitch-accent in native Japanese speakers.