Transfiguration process of west coast fishing industry in modern times is different from the south coast, and Japanese are encroaching on the west coast fishing ground because of the lack of croaker fishing ground and the use of common fishing ground, croaker production volume tribe, the activities of the fishes carrier. At that time Japanese fishing activities was allowed in the 4 province of Hamgyeong-do and Gangwon-do, Gyoengsang-do, jeolla-do 4 degree in 1882 the trade rules contracting. After appearance of the Japanese fisherman near the Gaeyado of Jeollabuk-do around 1890, Japan improved the Angangmang which hits to the west coast fishing ground and soothes Koreans` repelling the warship with the expedient which the west coast fishing ground with periodic and went round observed. Under Japanese imperialism policy like this the many fishermen did illegal fishing and strained the blown Pasi structure in the Chuchung-do and Gyoenggi-do, Hwanghae-do, Pyeongan-do. The points which comes to reveal from the research which are like this. First, the stow net fishing introduced in the west coast 1900 was improved under Japanese imperialism policy. From the area where stow net advances Japan provided a fishing industry grants for going out fishing fishermen in the Korea and encouraged the west coast fishing ground. Secondly, The fishing ground which the stow net fisherman went to the front was the uninhabited island not the main place of Korean croaker fishing ground and they had a snapper and croaker fishing around this place. These fishery could sell off every where because Koreans like the croaker most. The croaker compared in supply and the demand was insufficient absolutely and price rises, the croaker production volume of Korea was stalemate. Japanese fishermen supplied a many croaker and they transacted business with Korean merchant in these days. Thirdly, the stow net fishing was similar to the Jungsoen of the fishing methods which advances west coast fishing ground but the capital does not hold plentifully and fishing amount was hight. The Korean fishermen purchased the clipper and a phrase from the Japanese and went into stow net fishing in the Japanese main fishing ground like Island areas of Chungcheongnam-do. 30% of total stow net was Korean possession in the Japanese colonial period. Fourthly, as stow net and Jungseonmang to move the fishing ground along a tide in this way developed, the fishery base-like seasonal fish market that was different from seasonal fish market of the Chosoen period appeared in the west coast fishing ground. A temporary village was formed in the islands area of the west coast by a fishing boat and a business ship moved by croaker fishing season, and merchants moving in pursuit of them. As for the croaker fishery to move a school of fish later, the fishery base-like fishery that was in seasonal fish market form developed by the activity of the fishermen who went up it from the south with the Japanese fishermen who crossed it from Japan every year.