A communication circuit comprising: a first reference potential input terminal configured to receive a first reference potential; a first power supply potential input terminal configured to receive a first power supply potential different from the first reference potential by a predetermined potential; a second reference potential input terminal configured to receive a second reference potential; a direct-current converter circuit configured to receive the first reference potential, the first power supply potential and the second reference potential, and generate a second power supply potential different from the second reference potential by the predetermined potential, from the first power supply potential; a first receiving circuit configured to receive a first binary communication signal, whose one level is at the first reference potential, through a first signal input terminal, and to output a second binary communication signal (Inl) by a differential transmission method; a first level shift circuit configured to receive the second binary communication signal, the first reference potential, the second power supply potential and the second reference potential, and to convert the second binary communication signal (Inl) output by the first receiving circuit into a third binary communication signal, whose one level is at the second reference potential, and the other level is at the second power supply potential; and a first transmission circuit configured to receive the third binary communication signal converted by the first level shift circuit, the second reference potential and the second power supply potential, and to output a fourth binary communication signal, through a first signal output terminal, by a differential transmission method. a first reference potential input terminal configured to receive a first reference potential; a first power supply potential input terminal configured to receive a first power supply potential different from the first reference potential by a predetermined potential; a second reference potential input terminal configured to receive a second reference potential; a direct-current converter circuit configured to receive the first reference potential, the first power supply potential and the second reference potential, and generate a second power supply potential different from the second reference potential by the predetermined potential, from the first power supply potential; a first receiving circuit configured to receive a first binary communication signal, whose one level is at the first reference potential, through a first signal input terminal, and to output a second binary communication signal (Inl) by a differential transmission method; a first level shift circuit configured to receive the second binary communication signal, the first reference potential, the second power supply potential and the second reference potential, and to convert the second binary communication signal (Inl) output by the first receiving circuit into a third binary communication signal, whose one level is at the second reference potential, and the other level is at the second power supply potential; and a first transmission circuit configured to receive the third binary communication signal converted by the first level shift circuit, the second reference potential and the second power supply potential, and to output a fourth binary communication signal, through a first signal output terminal, by a differential transmission method.