A semiconductor memory device according to an embodiment of the present invention includes a first cell string and a second cell string coupled to a first word line group and a second word line group, respectively. An operating method of the semiconductor memory device may include forming a channel in the second cell string by applying a pass voltage to the second word line group, reflecting data of a selected memory cell coupled to a selected word line of the first word line group, among memory cells of the first cell string, on the channel of the second cell string through the bit line, and determining the data of the selected memory cell by sensing a quantity of electric charge of the second cell string through the bit line.