The purpose of the present study was to investigate the judgment-specific brain activity during audio-visual temporal order judgment task using functional magnetic resonance imaging (functional MRI). Twenty healthy volunteers were asked to judge whether visual and auditory stimuli were presented synchronously or not in a MRI. As the result, the frontal and parietal cortex, cerebellum and thalamus were significantly activated during audio-visual synchronization task. More importantly, the right ventral posterior parietal cortex was significantly activated only when subjects judged that the two stimuli were not synchronized. Therefore, activity in the right ventral posterior parietal cortex might be useful to estimate subjective judgments in audio-visual temporal order judgment task.