An audio signal processor includes: a first amplifier that amplifies a first audio content; a mixer that mixes an output signal of the first amplifier and a second audio content; a second amplifier that amplifies an output signal of the mixer; and a setter that sets an amplification amount of the first amplifier. The setter sets an amplification amount in the first amplifier so that the amplification amount in the first amplifier cancels an amplification amount in the second amplifier.