A semiconductor memory device includes a switching controller, a voltage generator and control logic. The switching controller is connected to a local word line. The voltage generator, connected to the switching controller, is configured to generate an operating voltage according to an input clock signal and transfer the operating voltage to the switching controller. The control logic is configured to control operations of the voltage generator and the switching controller. The control logic is configured to detect an amount of leakage current of the local word line by counting a number of pulses of the input clock signal.