To provide a transmission apparatus capable of improving effective usage of frequencies and efficiency of the transmission rate, and capable of improving communication quality by suppressing influence of interference waves.

Level measurement of an interference wave is performed using a receiving unit 15 for interference waves detection and a level detecting unit 41 to be provided in an interference detecting unit 16, then a transmission frequency to be usable by performing interference wave detection is calculated, the transmission is performed by determining a frequency band width to be used from data amount to be transmitted using a determining unit 52 and a spread switching unit 53 provided in a signal processing unit 19, and a transmission control unit 17.