A semiconductor integrated circuit device includes a first field-effect transistor and a second field-effect transistor, each of the first field-effect transistor and the second field-effect transistor having a gate electrode formed as a ring shape, a drain diffusion layer formed inside the gate electrode and a source diffusion layer formed outside the gate electrode and a substrate potential diffusion layer or a well potential diffusion layer disposed to contact each of the source diffusion layers of the first and the second field-effect transistors of the same conductivity type, the substrate potential diffusion layer or the well potential diffusion layer being formed with a semiconductor of a different conductivity type from the source diffusion layer. Different signals are input to each of the gate electrodes, the substrate potential diffusion layer or the well potential diffusion layer are formed between the source diffusion layer of the first field-effect transistor and the source diffusion layer of the second field-effect transistor.