PURPOSE: To eliminate the need for excessive framing reproducing control and to transmit only a data signal, by reproducing the framing with a receiver when a framing error takes place, in the signal transmitter transmitting plural words in the serial signal start-stop synchronizing system.

CONSTITUTION: When the framing is failed and the framing error signal 107 is outputted from an UART2, an output 104 of a D FF circuit 6 is logical 1 at the rise of the signal 107 and an OR gate 7 is closed. Then, a serial signal 100 is not transmitted to the UART2. Further, an FF circuit 5 is applied with a set signal 108 through an OR gate 9 when the signal 107 is outputted, the output signal 116 is logical 1 to inhibit the input of a parallel signal 105 from the UART2 to a register 3. In this state, when the serial signal applied to the terminal 1 falls down, this is regarded as a start pulse, the output signal 104 of the circuit 6 is made to logical O, the OR gate 7 is opened and the serial signal 100 is transmitted to the UART2.