A field experiment was carried out to clarify the effect of underwater sound on the luring of fish school. The effects of. the acoustic emission on the luring of fish school were checked actually at a set net fishing site in Namhae using a commercial acoustic equipment, Dairyo-8. An emitting system of sound was designed by the authors, and the ambient noise, the sound pressure level and the reaction of fish school were measured in the set net. 1. The predominent frequency band of ambient noise was 150Hz-400Hz,.and the sound emitted was 400Hz-100Hz. The sound pressure level of ambient noise in set net was higher at the landing part, and lower at the playgrond, the gate of court and "the enterance of inclined "passage. The ambient noise was increased with the time elapse-d at the stage of hauling net, but :it was decreased suddenly at the final stage due probably to the decrease of the swimming speed of the fish school. 2. The results of the observation and the recording paper of echo sounder indicate that the effect of emitting sound in the bag net of set net was remarkable for the luring of fish school in the early stage, but decreased after 30 minutes. The reaction of fish school is more sensitiv2 to the sound pressure level than the time intervals between the emission and the pause. For the purpos~ of practical use, it is nesessary to confirm what kind of sound pressure level is the best for the luring of fish school. 3. In response to the acoustic equipment(Dairyo-8), fish school started to swarm 20 minutes after the sound emission and scattered when the sound paused. As the emitting pattern of the acoustic equiment, the three seconds of emission after one second of pause was more effective than the continuous emission at the set net fishing ground. Catch of the fish(s during th~ sound ernissio:l at the gate of court was three to five times more than that of no emission.