In an emergency report apparatus, diagnostic data is modulated based on a preselected diagnostic modulation method by using a diagnostic carrier wave having a carrier wave frequency that is set within a range of frequencies detectable by a vehicle-mounted voice input instrument and is outside a voice band. A diagnostic electric signal is outputted to a voice output instrument. Demodulated data is generated by demodulating an input voice electric signal being a voice electric signal representing a voice detected by the voice input instrument based on a preselected diagnostic demodulation method. It is determines whether the demodulated data includes data that matches the diagnostic data.