A semiconductor device including a test circuit is miniaturized. The semiconductor device includes r first input terminals (r is an integer of 2 or more), a second input terminal, r functional circuits, a demultiplexer, and a switch circuit. The demultiplexer is a pass transistor logic circuit. R output terminals of the demultiplexer are electrically connected to respective input terminals of the functional circuit and the input terminal is electrically connected to the second input teiminal. Input terminals of the r circuits are electrically connected to the respective first input terminals through the switch circuit. For example, a signal for verification is input to the first input terminal in verification of the functional circuit to operate the demultiplexer. One signal for verification is input to r functional circuits by the demultiplexer.