This paper aims to investigate how the regional response to red tide occurrence is made in the aquaculture in Nyuzu District, Saiki City, Oita Prefecture. In this district, the periodical monitoring by administration and research institute and seminar about red tide by research institute were conducted. However, management entities did not necessarily depend on this collaboration system but both acknowledged red tide occurrence through appropriate channel and utilized their knowledge as needed acquired from the seminar to respond to red tide occurrence. Therefore, it can be concluded that in Nyuzu District, the regional response is made with the collaboration system among various actors utilized selectively by the situation management entities faced.