An object is to provide a semiconductor memory device which holds data of an SRAM or a flip-flop circuit and holds data in the SRAM while electric power is not supplied from a reader or electric power is not enough, without changing a battery for driving a power supply corresponding to deterioration of the battery with time, and a semiconductor device provided with the semiconductor memory device. An SRAM cell, a decoder connected to the SRAM cell through a word line, a read/write circuit connected to the SRAM cell through the data line, and a power storage unit connected to the SRAM cell are provided. The power storage unit is charged when data is written to or read from the SRAM cell through the data line.