A semiconductor device includes a test data interface, a first data interface, and a second data interface. The test data interface generates first test data and second test data from data inputted through a test pad in response to a test control signal and outputs failure information to the test pad in response to a read control signal. The first data interface generates first aligned data from the first test data or the second test data in response to the test control signal. The second data interface generates second aligned data from the second test data.