An operating method of a memory device, comprises: a program operation of applying a program voltage to a selected word line to program selected memory cells connected to the selected word line, a first verification operation of applying a first verification voltage to the selected word line and applying a first verification pass voltage to unselected word lines to verify a first program state of the selected memory cells, and a second verification operation of applying a second verification voltage to the selected word line and applying a second verification pass voltage to the unselected word lines to verify a second program state higher than the first program state.