To provide the active sound eliminating device which can reduce the whole noise radiated by equipment, etc., placed in a three-dimensional space under automatic control in simple constitution.

This device is equipped with an additional sound source (speaker) 32 arranged nearby a noise source 31, acoustic power measuring means (microphones 33 and 34) which measure the acoustic power from the additional sound source 32 due to interference between the noise source 31 and additional sound source 32, and a control means 35 which controls the output of the additional sound source 32 so as to minimize the acoustic power measured by the means. Consequently, control for minimizing the acoustic power radiated by the additional sound source is performed, and consequently the total acoustic power of the noise source and additional sound source becomes minimum. Consequently, the noise radiated by the noise source to the circumference is effectively reduced, which greatly contributes greatly to sound elimination.