To provide a novel communication system that is superior in confidentiality.

A reception electrode 4 is arranged close to a transmission electrode 2 with an insulating layer in between. A first voltage impression section 10 applies a specified first fixed voltage to the reception electrode 4 in first condition, and applies a second fixed voltage lower than the first fixed voltage in second condition. A second voltage impression section 12 applies a second fixed voltage to a reference electrode 6 of a reference capacitor 32 in first condition, and applies a first fixed voltage in second condition. A first sample hold circuit 14 averages voltages Vx1 and Vx2 that appear in the reception electrodes 4 and 6 in the first condition, and holds it as a first detected voltage Vdet1. A second sample hold circuit 16 averages voltages Vx1 and Vx2 that appear in the reception electrodes 4 and 6 in the second condition, and hold it as a second detected voltage Vdet2. An amplifier 20 amplifies a potential difference between the first and second detected voltages Vdet1 and Vdet2.

COPYRIGHT: (C)2010,JPO&INPIT