According to an embodiment, a nonvolatile semiconductor memory device comprises a plurality of conductive layers stacked in a first direction via an inter-layer insulating layer. In addition, the nonvolatile semiconductor memory device comprises: a semiconductor layer having the first direction as a longer direction; a tunnel insulating layer contacting a side surface of the semiconductor layer; a charge accumulation layer contacting a side surface of the tunnel insulating layer; and a block insulating layer contacting a portion facing the conductive layer, of a side surface of the charge accumulation layer. Moreover, the portion facing the conductive layer, of the charge accumulation layer is thinner compared to a portion facing the inter-layer insulating layer, of the charge accumulation layer.