To obtain a mobile object radio system such as a train radio system capable of testing a state of communication to be performed by a control line and a sound line between communication equipment and radio equipment provided in a moving object such as a train and outputting a test result to a user.

A control test signal is transmitted to pieces of radio equipment 11, 13 of trains 12, 14 by a control line 15 and a sound test signal is transmitted to the radio equipment by a sound line 16 according to an instruction from the user by a test signal transmitting means at pieces of communication equipment 2, 8. When the control test signal is received by a control test signal receiving means, a response signal is transmitted to the communication equipment by the control line by a response signal transmitting means and the sound test signal is returned to the communication equipment by the sound line by a sound test signal returning means at the radio equipment. The response signal is received by a response signal receiving means, the sound test signal is received by the sound test signal receiving means and information regarding receiving states of the response signal and the sound test signal is outputted to the user by an output means at the communications equipment.