To provide a transmission apparatus which can be easily designed and assembled and which can easily harmonize the redundancy with the immediacy of data transmission.

The transmission apparatus is called at a constant processing period (tpc), receives analog information (S110), detects the change in the analog data received this time and newest transmission data stored in a transmission data memory 8 from the difference between both data (S120), and uses the detected change for an input value to decide a transmission interval (S130). The decided transmission interval and the timer value of a timer 5 are compared, and when the timer value elapses more than the transmission interval (YES in S140), the analog data this time are stored in the transmission data memory 8 (S150), and the timer value of the timer 5 is reset and restarted (S160). Then a transmission handler section 9 is started to transmit the transmission data stored in the transmission data memory 8 (S170).