A semiconductor device includes multiple memory cells, a first and second digit lines, where either of them is coupled to the memory cell to be read, a sense amplifier having a first and second sense nodes that are respectively connected to the first and second digit lines, a first switch between the first digit line and the first sense node, a second switch between the second digit line and the second sense node, and a control circuit that outputs a first and second control signals for controlling a conducive state of the first and second switches. When an activation of the sense amplifier is started, the control circuit makes the first and second switches conductive and disconnects the first or second switch corresponding to the digit line to which the memory cell to be read is not connected according to a potential difference between the first and second sense nodes.