Abstract: An auto tracking apparatus for automatically controlling tracking by using the head switching pulse and the envelope waveform of the composite video signal which is generated by a reproducing head. The auto tracking apparatus includes, an envelope detection means for detecting the envelope waveform of the frequency modulated signal detected by the reproducing head, a waveform shaping means for shaping the envelope waveform detected by the envelope detection means into a direct current, a second amplifier means for amplifying a pulse train generated in response to a head switching pulse, and for filtering the pulse train, a comparator means for comparing the filtered sampling pulse with the signal outputted from the second amplifier means, and for outputting the pulse as a different duty cycle, and microcomputer means for controlling the servo stage based on the output signal from the comparator means, sampling the head switching pulse with a constant interval, and supplying it to the second amplifier means.