1. An interference reducing apparatus comprising: a superimposition amount determining unit, in the case of receiving a voice including an utterance voice uttered by a user speaker and an interference signal, which estimates an interference component that interferes with recognition of said voice from information based on a position of a speaker or an utterance distance, and obtains a reduction signal of reducing influence of said interference component in said recognition of said voice by superimposing said reduction signal onto said voice; and a reduction signal superimposing unit which superimposes said reduction signal on said voice and output the superimposed voice.