The input/output nodes of memory cells connected in series are connected to bit lines. Two of the bit lines positioned on the outsides of four successive memory cells constitute each of a plurality of bit line pairs. The bit line pairs are connected to four data lines, respectively, via switches connected to the respective bit lines. A switching control circuit turns on adjacent five of the switches. A switching circuit connects the data lines connected to the input/output nodes by the turning-on of the switches to a supply node of a first voltage, a supply node of a second voltage, and first and second sense amplifiers, respectively. Thereby, data is read from two of the memory cells simultaneously. Thus, it is possible to read data from the two memory cells simultaneously by using the simple switching control circuit without increasing the chip size.