Neural stem cells (NSCs) in the adult hippocampus divide infrequently; the endogenous molecules modulating adult hippocampal neurogenesis (AHN) remain largely unknown. Here, we show that ErbB3 binding protein 1 (Ebp1), which plays important roles in embryonic neurodevelopment, acts as an essential modulator of adult neurogenic factors. In vivo analysis of Ebp1 neuron depletion mice showed impaired AHN with a low number of hippocampal NSCs and neuroblasts. Ebp1 leads to transcriptional repression of Bmp4 and suppression of Ascl1 promoter methylation in the dentate gyrus of the adult hippocampus reflecting an unusually high level of Bmp4 and low Ascl1 level in neurons of Ebp1-deficient mice. Therefore, our findings suggests that Ebp1 could act as an endogenous modulator of the interplay between Bmp4 and Ascl1/Notch signaling, contributing to AHN.