In a notifying device comprising a notifying unit 2 having incorporated therein a vibrator to be resonated by a drive signal fed thereto, and a signal preparing circuit 5 for feeding the drive signal to the notifying unit 2, the signal preparing circuit 5 prepares a drive signal Dv varying in frequency within a predetermined range including the resonance frequency of the vibrator of the unit 2 and feeds the signal to the notifying unit 2. The variation of frequency of the drive signal is determined in correspond relation with a variation in the resonance frequency of the vibrator due to tolerances for specifications which govern the resonance frequency. The drive signal has an alternating waveform of rectangular waves or sine waves, and the frequency thereof varies periodically from 1.37 to 2.98 Hz. The notifying device achieves a satisfactory notifying effect despite the variation of the resonance frequency of the vibrator.