An input/output (I/O) line sense amplifier includes a buffer unit, a sense amplifier, and a precharge unit. The buffer unit is driven by a first level voltage to buffer a strobe signal, and the sense amplifier is driven by a second level voltage to amplify a signal of an I/O line in response to an output signal of the buffer unit. The precharge unit is driven by the first level voltage to precharge an output signal of the sense amplifier in response to the output signal of the buffer unit.