Social interaction is largely facilitated by spatiotemporal contiguity among individuals. The brain area called the mirror neuron system (MNS), which is activated when an individual observes the actions of others, as well as when they perform the same action themselves, is considered to play a crucial role in social cognition. The present study investigated whether and how the MNS activity is influenced by temporal contiguity between the observer and observee: (1) live face-to-face, (2) live video-mediated, (3) 6s-delayed video-mediated, and (4) prerecorded action observation conditions. ANOVA revealed that there was a significant modulation by the conditions. MNS activity in the live face-to-face condition was significantly larger than that in the prerecorded condition. A moderate activity was observed in the live and 6s-delayed video-mediated conditions. These results indicate that MNS activity is sensitive to the temporal contiguity, which likely affects the quality of social interaction.