A peak suppressing apparatus includes an amplitude limiter that limits amplitude of the transmission signal with a predetermined threshold; a peak-suppressing-signal extracting unit that extracts a peak suppressing signal by subtracting the transmission signal before the amplitude limiting from the transmission signal amplitude-limited by the amplitude limiter; a filtering unit that performs filtering so that a frequency characteristic of the peak suppressing signal extracted by the peak-suppressing-signal extracting unit becomes flat; and an adder that adds the peak suppressing signal filtered by the filtering unit to the transmission signal.