For the continuous recording of the sea noise which are caused by several sound sources such as moving vessels and fishing gears with complicated motion in the sea, the present method to collect information through the cable between the hydrophone and the recorder on deck of the ship is slightly difficult for use. Therefore, the authors have built newly the underwater tape-recorder as the system of direct recording without cable which can be easily attached to these moving objects. The new apparatus was shackled to the head-rope of the square part of the trawl-net, and the sea noise under trawling was recorded at the mouth of the trawl-net by it and in the laboratory was analyzed by the soundspectrograph. Here have been reported the techinical consideration on it and some of the results. 1. Underwater tape-recorder was effective sufficiently for the recording of the sea noise which was caused by moving fishing gears and others. 2. After several acoustic experiments, the calibration of the absolute sound pressure is given in decibel re 1μ bar on this report. 3. On the sound spectrum, the frequency distribution of the sea noise, which recorded at moving net of the otter trawler and of the two boat trawler, is ranged over DC to 5, 000Hz and the dominant frequency zone is the range of 500Hz to 700Hz. And then the sound pressure is about 21dB on the otter trawler and about 11dB on the two boats trawler, 4. Some of misagreements on the sea noise between otter and two boats trawler are recognized: at the range of low frequency the noise of two boats trawler is shown lower level of sound pressure than otter trawler, but at the high frequency range is shown inversely.