Dopamine in the prefrontal cortex is essential for the regulation of social behavior. However, stress-causing social withdrawal also promotes dopamine release in the prefrontal cortex. Thus, this evidence suggests opposite functions of dopamine in the prefrontal cortex. However, the influence of dopamine on prefrontal functions is yet to be fully understood. Here, we show that dopamine differentially modulated the neuronal activity triggered by social stimuli in the prefrontal cortex, depending on the duration of the dopamine activation (transient or sustained activation). Using chemogenetic techniques, we have found that social behavior was negatively regulated by a sustained increase in dopamine neuronal activity in the ventral tegmental area, while it was positively regulated by an acute increase. The duration of social interactions was positively correlated with the transient dopamine release triggered by social stimuli in the prefrontal cortex and negatively correlated with the sustained increase in prefrontal dopamine levels. Furthermore, the elevation of neural calcium signal, triggered by social stimuli, in the prefrontal cortex was attenuated by the persistent elevation of prefrontal dopamine levels, whereas an acute increase in dopamine levels enhanced it. Additionally, the chronic excess of dopamine suppressed c-Fos induction triggered by social stimuli in prefrontal neurons expressing dopamine D1 receptors, but not D2 receptors. These results suggest that sustained activation of prefrontal dopamine, at the opposite of its transient activation, can reduce prefrontal activity associated with social behavior, even for identical dopamine concentrations. Thus, dopamine plays opposite roles in modulating prefrontal activity depending on the duration of its action.