Virgin male mice show aggressive behaviors toward pup. After mating with female, they gradually stop infanticide and show paternal behaviors. The rhomboid nucleus of the bed nucleus of the stria terminals (BSTrh) is activated by pup-exposure to virgin male, but not paternal mice. We previously showed that the amplitude of electrically evoked inhibitory postsynaptic potentials in BSTrh neurons of paternal mice is larger than those of virgin male mice. In this study, we examined the source of inhibitory inputs to the BSTrh activated during paternal behaviors. Adeno-associated virus vector was infused into the central amygdala (CeA) to express channelrhodopsin 2 (ChR2). Few weeks later, we prepared brain slices and performed whole-cell patch-clamp recordings from the BSTrh neurons. Light stimulation to the ChR2 located on the nerve fibers projectiong from the CeA to the BSTrh evoked monosynaptic inhibitory postsynaptic responses. To address whether the CeA neurons are activated during paternal behaviors, we infused retrograde tracer into the BSTrh and examined the pup-induced cFos expression in the CeA. We observed more cFos- and tracer-double- positive CeA neurons in the pup-exposure group compared with the control group. These data suggest that CeA neurons are activated during paternal behaviors to suppress the BSTrh neruons.