To allow sure switching of a characteristic fluctuation of a monitoring transistor to the other block before characteristic fluctuation of a circuit transistor by a method wherein a transistor for monitoring a characteristic fluctuation has a substrate current larger than the substrate current of the transistor for the circuit of a semiconductor device.

A semiconductor device is formed on the (100) plane wafer and a channel direction of the transistor Tr is to be <100> direction or a direction equivalent thereto. A channel direction θ of a transistor MTr for characteristic fluctuation monitor is to be directed in the <110> direction or a direction different from equivalent direction thereto. Then, a substrate current is to be 1.1-2 times as large as the circuit transistor Tr. Thereby, characteristic fluctuation of the transistor for monitoring can be switched to the other block not too early than besides in advance of sure characteristic fluctuation of the transistor for circuit.