The purpose of this study was to investigate the importance of the professional knowledge of the trainer in health club. Every manager do his best to attract the members because the period of recreation come and the industry of healthy develop. And the paper investigated the importance of the professional knowledge by the trainer that was closely to members. It discussed the importance by the satisfaction of members and the motive of participation. And it revealed that the professional knowledge of the trainer affected the working in health club. Finally, the study recommends: 1. To the manager, it could have the united system of education. 2. To the researcher, it could research further. 3. It must be the supervised role to the professional knowledge of the field to the government.