PURPOSE: To attain sure data input even if key operation is executed in plural remote controllers at the same time by outputting repetitively a transmission data of plural sets of the remote controllers at each different period.

CONSTITUTION: One end of ten-keys K0∼K9 of a key input section 5a is connected to data forming circuits 310∼319 in a data transmission circuit 11a. A reference frequency signal outputted from an oscillator 32 is frequency-divided into a 40kHz by a frequency division circuit 33, further frequency-divided into a 1kHz signal at a frequency division circuit 34 and then inputted to a clock terminal CK. The data forming circuit forms data of 0∼9 depending on the operation of the ten-keys K0∼K9 and inputs them to an AND circuit 36 via an OR circuit 35. An output of the AND circuit 36 is inputted to a gate of an output transistor 12a via an inverter 37 and a resistor 38 and an infrared ray LED 13a is driven. Thus, the data is transmitted and received by a photodiode of the reception circuit.