Abstract: A video signal frequency modulator having an automatic control function includes a reference generator for generating a sync tip level signal and a white peak level signal, a first switch for selecting one of the sync tip level signal, white peak level signal or a clamped video signal according to a mode control signal, a variable gain amplifier for amplifying the output of the first switch to a predetermined gain and converting the amplified result into a current, an adder for adding the output of the variable gain amplifier with a predetermined set value, an oscillator for frequency-modulating the output of the adder, a frequency detector for shaping and frequency-dividing the output of the oscillator, a microcomputer for comparing the output of the frequency detector with a predetermined reference frequency and outputting first and second control data and the mode control signal, a carrier frequency setting portion for controlling the magnitude of the predetermined set value according to the first control