A semiconductor device with improved generation function of unique information is provided. The semiconductor device includes an integrated circuit designed or fabricated based on a general design condition or manufacturing condition, an input/output circuit, and a unique-information generation circuit to generate unique information of the semiconductor device. The unique-information generation circuit includes a circuit for PUF and a code-generation unit. The circuit for PUF is fabricated based on the design condition or manufacturing condition which is different from the general design condition or manufacturing condition and has a factor which makes variations of circuit components become large. The code-generation unit generates codes based on the output of the circuit for PUF.