A contactless electronic device comprises a semiconductor integrated circuit device, a plurality of antennas (or antenna coils) for receiving high-frequency signals supplied by radio waves or electromagnetic waves having different frequencies. An interface judgment circuit judges which antenna the high-frequency signals are inputted through, and according to a result of the judgment, the operation of the semiconductor integrated circuit device is changed. In this manner, the contactless electronic device becomes possible to respond to a plurality of communication protocols using high-frequency signals having different frequencies, while contactless electronic devices have been impossible to respond to communication protocols using various high-frequency signals.