A float gate memory device comprises a bottom word line, a float channel layer formed on the bottom word line and kept at a floating state, a float gate, and a top word line formed on the float gate in parallel with the bottom word line. In the float gate formed on the float channel, data are stored. Here, data are written in the float gate depending on levels of the bottom word line and the top word line, and different channel resistances are induced to the float channel depending on polarity states of charges stored in the float gate, so that data are read. As a result, in the float gate memory device, a retention characteristic is improved, and cell integrated capacity is also increased due to a plurality of float gate cell arrays deposited vertically using a plurality of cell oxide layers.