A semiconductor device includes two or more memory chips electrically coupled. Each of the memory chips includes global lines, a MUX unit, a selection unit, and an output unit. The global lines transmit data stored in memory cells. The MUX unit receives the data loaded onto the global lines to output a test data. The selection unit is inserted into two or more of the global lines and configured to output the test data instead of the data loaded onto the two or more global lines, in a test mode. The output unit is coupled to the global lines and is configured to output the data in a normal mode, and output the test data received from any one of the two or more global lines connected to the selection unit to an I/O pad based on information about the memory chip in a test mode.