To easily add a function for correcting an error due to noise with a radio system, such as multiple paths by permitting selected signals which are transmitted from slave stations to have a redundancy degree, converting them into multi-bit group signals and transmitting them to a master station as transmission data.

Slave stations 1 are terminal equipment, where plural depression switches 101 for selecting an answer by a user and the display lamp 121 of LED are arranged. Although the master station 2 is connected to a personal computer 3 it is the portable personal computer, and it is provided with a PC card slot 301. Each slave station 1 encodes a selected signal into a prescribed bit group signal, modulates it into a prescribed time slot assigned to the station 1 for radio communication, and transmits it to the master station 2 as transmission data. The master station 2 successively receives transmission data form the slave stations 1, respectively demodulates them into the bit group signals, and then decodes the selected signals of the slave stations 1 which are the bit group signals by referring a conversion table disposed in the master station.