A non-volatile semiconductor memory device that can reduce power consumption includes plural memory banks containing nonvolatile plural memory cells. A common data bus is shared by plural memory banks and transmits the data of the memory cells. The plural switches are provided respectively between the electric source and plural memory banks. A controller controls the plural switches. The controller, in the data reading-out action or the data writing-in action, makes at least one of the switches corresponding to at least one of the memory banks accessible in a conduction state, and other switches in a non-conduction state.