Since the working machine generates an excessive loud noise as much as its use-purpose and dimension, those damages are occurring to the exposed workers such as unpleasant sense, stress and occupational hearing-impaired. Accordingly, as one of the measures for prevention such loud noise, various soundproof protection tools were developed. However, such soundproof protection tools were presented the physical measured value only, it is real state that the psychological study result with regard to the soundproof effect which the workers are actually feeling, is not existing. On such point of view, with the object on the typical earplugs and earcaps among the soundproof protection tools, this study has ever tried a subjective evaluation about the degree of soundproof effect through Psycho-acoustics experiment. It is considering that such study result could be utilized as the useful material when establishing the soundproof measure for the workers in the future.