Typhoons threatening Korea occasionally bring about one of the most extreme nation-wide disaster accompanied by strong gust and heavy rainfall during the summer to early autumn. Generally, the intensity of the typhoon is very important in the disaster estimation along with its ground track or landfall. Most of the typhoons heading for Korean Peninsula should take their route through the East China Sea (ECS). Typhoon Ewiniar 2006 (Ewiniar for brevity, hereafter) was the third named tropical storm of the 2006 Pacific typhoon season and one that lasted for twelve days as a tropical cyclone moving generally northward until it made a landfall on the western region of Korea. Evidences of the interaction between the typhoon Ewiniar and ECS has been investigated analyzing the fixed-point observation at Ieodo Ocean Research Station(IORS) and satellite derived SST data. Since the Ewiniar's eye was so close to the IORS, marked cooling of the SST has well detected. The cooling of upper ECS seems not happened along the entire Ewiniar track in the ECS. Waters around ECS shelf near to IORS affected much by the typhoon Ewiniar because of relatively shallow depth with thin mixed layer as well as cold bottom waters underlying it. It should be noted that this strong influence of the typhoon Ewiniar on the ECS shelf plays a negative feedback to the Ewiniar intensity resulting in rapid weakening of its strength. The most important parameter on this strong interaction between Ewiniar and the ECS shelf is the typhoon translation speed; the slower the typhoon the stronger the interaction between the typhoon and the sea.