Disclosed is an apparatus for converting a frequency. The apparatus includes: an oscillator configured to generate a first oscillation signal having a first oscillation frequency which is obtained by subtracting an input frequency from a carrier frequency of any one carrier signal among a first to a n-th carrier signals (n is a natural number), and generate a second oscillation signal having a second oscillation frequency which is obtained by adding the input frequency to a carrier frequency of any one carrier signal among a (n+1)-th to a 2n-th carrier signals; and a mixer configured to mix and output the first oscillation signal or the second oscillation signal with an input signal having the input frequency.