A method of providing an operating voltage in a memory device includes applying a read voltage to a selected word line while applying a first pass voltage to at least one unselected word line among word lines adjacent to the selected word line; and while applying a second pass voltage to the remaining unselected word lines (other than the at least one unselected word line to which the first pass voltage is applied). The level of the first pass voltage is higher than the level of the second pass voltage. The level of the first pass voltage may be set based on the level of the read voltage.