Early social experience is critical for development of social and emotional functions, and social adversity in early life induces social and emotional dysfunctions in rodents and human. However, its underlying neural mechanisms are poorly understood. Recently, the orbitofrontal cortex (OFC) and amygdala have been highlighted as key nods for social and emotional functions. In this study, we examined effects of adolescent social isolation on synaptic transmission in the OFC-basolateral amygdala (BLA) pathway in mice. We isolated male C57BL/6J mice during adolescence and evaluated social and emotional behaviors and synaptic function after maturation. Isolated mice decreased social preference in the social interaction test and increased passive-coping behavior in the tail suspension test. Next, we examined synaptic transmissions to BLA from medial or lateral subregions of the OFC (mOFC or lOFC) by optogenetic and patch-clamp methods. Interestingly, AMPA/NMDA ratio in mOFC-BLA synapse was decreased in the isolated mice, while the ratio was increased in lOFC-BLA synapse. Furthermore, optogenetic manipulations of the mOFC-BLA and lOFC-BLA transmissions altered social preference and passive-coping behavior in a different manner. Our results suggested adolescent social isolation disrupted OFC-BLA synaptic function by subregion-dependent effects and induced social and emotional abnormalities in socially isolated mice.