This study analyzed a five-year adult learning course focusing on conservation of the natural environment in suburban area. The course included field trip activities involving visits to certain communities to observe their environmental conservation efforts, as well as observations of the natural environment and landscape of participants’ community. Our analysis sought to determine whether field trips lead to acquisition of knowledge of action strategies for conservation of the natural environment. Data obtained from 124 descriptions of impressions written by members were divided into individual words through text mining. Cluster analysis using 63 words with high appearance frequency revealed nine themes. Two themes, “Activities/Programs of Conservation” and “Citizen Participation,” suggested that the trips facilitated opportunities for the participants to witness citizen volunteers and government officials together creating conservation plans and managing the parks and conservation areas to conserve the natural environment. It is suggested that the community regime on citizen’s participation contributing to the successful policy and action, as collaborative planning for conservation, is important for the acquisition of action strategies for environmental conservation. These findings implied that acquiring information about citizen participation influencing the process of successful environmental policy and action is important in education focusing on environmental behavior. Statistical analysis revealed that the occurrence ratios of both themes, “Activities/Program of Conservation” and “Citizen Participation”, were relatively higher in educational programs for visits to other communities than in other programs such as lectures and environmental surveys of their community. Additionally, both themes were closely related to the “Action/Attitude” word group. Thus, field trips enabled participants to understand the importance of community participation and learn of environmental action strategies through observing effective policies and citizen participation.