A memory device includes a memory cell array having multiple memory cells arranged respectively in regions where first signal lines cross second signal lines. The memory device further includes a decoder having multiple line selection switch units connected respectively to the of first signal lines. Each of the multiple line selection switch units applies a bias voltage to a first signal line corresponding to each of the multiple line selection switch units in response selectively to a first switching signal and a second switching signal, voltage levels of which are different from each other in activated states.