A semiconductor device and a system including the semiconductor device are disclosed, which relate to a technology for detecting a defective or failed part during a probe test of the semiconductor device. The semiconductor device includes a test controller configured to perform counting of a read flag signal during activation of a test signal and to control a data mask signal to be toggled at an N-th activation time of the read flag signal. The semiconductor device further includes a cell array configured to receive and store an output signal of the test controller through a data line during a write operation and to output the stored data to a test device during a read operation.