A mobile radio system includes a base station and a plurality of mobile radio apparatuses, with each mobile radio apparatus including a control CPU for controlling the mobile radio apparatus and monitoring the state of the hardware of the mobile radio apparatus, a transmitter unit for transmitting data in the form of radio waves, and a CPU monitor unit. The control CPU regularly monitors and checks for any abnormalities in the hardware of the mobile radio apparatus, and the CPU monitor unit regularly monitors and checks for any abnormalities in the control CPU. If there is an abnormality, a disabled transmission out put acceptance signal is supplied to the transmitter unit to inhibit or suppress the output of radio waves thereby avoiding interference to the system caused by unnecessary radio wave transmission from an abnormal mobile radio apparatus.