Nonvolatile semiconductor memory devices for preventing read disturbance and read method thereof

A nonvolatile semiconductor memory device and a reading method thereof are provided to prevent a reading disturbance due to a leak current by supplying a predetermined positive voltage to a common source line. Memory cells of a memory cell array(210) have NAND or NOR structure. A control logic(220) controls overall operation of a nonvolatile memory device(200), and controls operation related to read and verify read. A voltage generator(230) generates voltages supplied to a selected word line, an unselected word line, a string select line, a ground select line, and a common source line. A row decoder(240) drives the selected word line, the unselected word line, the string select line, the ground select line, and the common source line in response to a row address. A page buffer(250) is operated as a sensing amplifier or a write driver. A column decoder(260) reads data stored in the page buffer in response to a column address.