Relationship between cooperative-member is very important for cooperatives to continue their activities successfully and effectively. Effective management of cooperative depends on participation of members in the process of cooperative management. The desire to participate in the management varies according to person to person. The main purpose of this study is to determine members’ organizational trust level and examine the willingness to participate of members’ into the decision making process according to organizational trust level. Interviews were conducted with142 members in Izmir. Organizational Trust Inventory (OTI) was used. Factor analysis and cluster analysis were used to divide into groups to members’ organizational trust level. It has been determined that the members in the “non-trusting” group are more willing to participate in the management. Age, education and organizational trust, etc. have affected a willingness to participate in cooperative management. Professional management is necessary in order to raise economic and social profit of members. Cooperative leaders should not ignore the opinions of its members and they should also maintain good contact with members.