A semiconductor device includes the following elements. A sense amplifier amplifies signal on a bit line. A column switch is between the bit line and a local input-output line. A sub-amplifier amplifies signal on the local input-output line. A write switch is between the local input-output line and a main input-output line. A write amplifier amplifies write data and supplies the amplified write data to the main input-output line when data write operation is performed. A test circuit activates the sense amplifier while the test circuit deactivating the sub-amplifier and the write amplifier when a data read operation is performed in test mode. The test circuit places the column switch and the write switch in conductive state.