As for the Jinhae bay in 2010, hypoxia under DO concentration 3 mg/L began to form from the station where thermocline formed in the early June, and hypoxia disappeared in the late October as thermocline did. DIP and DIN was much higher in the bottom water of the sea where hypoxia occurred, and pH showed its low distribution. IL, COD and AVS of the surface sediment were shown relatively high at the station which is affected by the inflow of land water from the bay Masan bay and at the station where hypoxia remains for a long time. As for benthos distribution, macrobenthos never appeared at the survey station 8 and 23 which are near the bay Hangam bay and Gohyeonseong bay and macrobenthos appeared most diversely at the survey station 11 where hypoxia did not occur. Density was also minimum at the survey station 19, 21, and 23 where hypoxia occurred, whereas density was relatively high at the survey station 11, 13 and 14 where oxygendeficient phenomenon did not occurred. Meanwhile, biomass was lowest at the survey station 23 which is affected by sewage coming from the bay Wonmun bay and shipbuilding industry, whereas biomass was highest at the survey station 14 and 11. As for benthos of the Jinhae bay, species richness and diversity was relatively high at the survey station 11, 12, 13 and 14 where hypoxia did not occur, and thus it showed relatively good benthic community structure. Like this, hypoxia appears in the bay Jinhae bay for about 5 to 6 months annually, and during that period, most of the marine environmental factors appear to be abnormal. Therefore, we need the fundamental measures to reduce hypoxia for the purpose of producing marine products continuously.