To provide the optical signal transmitter or the like, in which a signal is continuously reproduced even when a transmission line is tentatively interrupted.

The device uses a delay memory 101 to delay time series digital data S11 to generate data S12, a multiplexer 102 multiplexes the two digital data S11, S12 and the result is sent into air as an infrared ray. An error- correcting circuit 154 applies error correction to the transmitted signal and provides an output of multiplexed data and provides an output of an error detection signal that denotes a correction disable state due to the interrupted transmission line. A demultiplexer 155 demultiplexes the received multiplexed data into digital data S15, S16, a delay memory 156 is used to delay the data S16 to make the time bases of the two data to match each other. A data selector 157 selects one of the two digital data S15, S17, on information of the error transmission signal.