An apparatus and method of oscillating a wideband frequency are disclosed. The apparatus includes: a frequency oscillating unit for oscillating a predetermined frequency; a phase-locked loop for comparing the oscillated frequency and a reference frequency by feed-backing the oscillated frequency from the frequency oscillating unit and fixing an oscillating frequency of the frequency oscillating unit; and a variable dividing unit for varying a division ratio to approach to a frequency band required by the oscillating frequency and dividing the oscillating frequency.