A method of and an apparatus for controlling noise generated in a confined space, being capable of reducing a radiating sound pressure generated from a main noise source (3) to that of an optimal state. The method includes the steps of measuring (4) the radiating sound pressure generated from the noise source (3), and generating, from an additional sound source (1), a radiating sound pressure having the same magnitude as the radiating sound pressure generated from the noise source (3) while having a phase 180 DEG -shifted from that of the noise source's radiating sound pressure so that the radiating sound pressures can offset each other when they are mixed. The apparatus includes an additional sound source (1) installed in the confined space, an intensity converter (11) for collecting and measuring sound pressure signals respectively generated from the noise source (3) and the additional sound source (1), and a microcomputer for applying, to the additional sound source (1), a control signal for reducing the noise on the basis of the sound pressure signals measured by the intensity converter (11).