The timing intervals initiated by voluntary pressing actions are subjectively compressed compared with those initiated by voluntary releasing actions. Event-related potentials (ERPs) were employed in the present study to uncover the temporal mechanisms underlying this temporal illusion. The results revealed that the mean amplitude of the P1 component over the frontal-central recording sites, but not the P2 component, was larger in the voluntary pressing condition than in the voluntary releasing condition at the time perception stage. In the fronto-central region, increases in oscillatory activities of delta-theta frequency range (1-7 Hz) were found in the voluntary pressing condition, which corresponded with the emergence of the P1 peak. In addition, the P1 amplitude was negatively related to the corresponding reported time length at the single-trial level. These results are discussed in terms of the functional role of the response-locked P1 in the time perception stage.