An acoustic data processor according to the present invention is used for processing acoustic data including signal sounds to reduce noises generated by a mechanical apparatus. The acoustic data processor includes a motion status obtaining section for obtaining motion status of the mechanical apparatus, an acoustic data obtaining section for obtaining acoustic data corresponding to the obtained motion status, and a database for storing various motion statuses of the mechanical apparatus in a unit time and corresponding acoustic data as templates. The acoustic data processor further includes a database searching section for searching the database to retrieve the template having the motion status closest to the obtained motion status; and a template subtraction section for subtracting the acoustic data of the template having the motion status closest to the obtained motion status from the obtained acoustic data to reduce noises generated by the mechanical apparatus.