This invention is directed to a wireless apparatus to carry out transmission and reception by either a digital communication system or an analog communication system and, in particular, provides a technical method to change over a signal system for a transmission electric wave. Concretely, when a carrier is received, a switch (PTT) is pushed in the case of response. In this case, if a default set transmission signal system is different from a reception signal system of a received audio signal, it is possible to modulate the audio signal after the transmission signal system is changed over to the same signal system as the reception signal system. Thus, a wireless apparatus is provided for making it possible to promptly change over a signal system of a transmission electric wave without doing troublesome operations.