A memory device includes a first insulating layer, a second insulating layer, an isolation layer, a floating gate electrode, a control gate electrode, a channel layer and a tunneling oxide layer. The second insulating layer is disposed adjacent to and substantially parallel with the first insulating layer to form an interlayer space there between. The isolation layer is disposed in the interlayer space to form a non-straight angle with the first insulating layer, and divides the interlayer space into a first recess and a second recess. The floating gate electrode is disposed in the first recess. The control gate electrode is disposed in the second recess. The channel layer is disposed on an opening surface of the first recess and forms a non-straight angle with the first insulating layer. The tunneling oxide layer is disposed between the channel layer and the floating gate electrode.