We examined whether the onset/offset of a stimulus affects audio-visual synchrony perception. The visual stimulus was a white light-emitting diode (LED). The auditory stimulus was a 1000-Hz tone that was presented through headphones. The stimulus duration was about 2 s in each modality. In all experiments, we measured the point of subjective simultaneity (PSS) using two tasks––a stimulus judgment task and a temporal order judgment task––using the method of constant stimuli. For each trial, a tone–light pair was presented or made to disappear with a lag that was chosen randomly from among nine values (-200, -150, -100, -50, 0, +50, +100, +150, +200 ms; a negative sign indicates whether the auditory stimulus appeared or disappeared first). In Experiment 1, we used the stimulus judgment task to examine the PSS for onset and offset of the audio-visual pair: participants made a yes–no judgment about whether the stimulus appeared or disappeared in synchrony. Results of Experiment 1 show that the PSS for onset timing was about -48.2 ms; that for offset timing was about +50.6 ms. For Experiment2, we used a temporal order judgment task to measure subjective simultaneity: participants judged whether a tone or light appeared or disappeared first. Results of Experiment 2 showed that the PSS was about -55.2 ms lag for stimulus onset timing. In contrast, it was about -4.6 ms for stimulus offset timing, suggesting that audio-visual synchrony perception processes differ between onset and offset of stimuli.