The objective of this study was to evaluate observer's impressions of roost containing behavior and to assess the effectiveness of awareness efforts regarding the conservation of the barn swallow (Hirundo rustica), which is endangered in Japan. In Kanagawa Prefecture retarding park, a group of observers habitually meets to observe the roost containing of the barn swallow, and a questionnaire was administered to 97 participants recruited from this group. Analysis using the semantic differential method revealed the impressions of swallow roost containing to be as follows: 1) There was a high tendency to have a positive impression with or without observation experience. 2) There was a tendency to feel the beauty, a sense of oneness with nature and the life force. The questionnaire description had many comments that awareness regarding swallow conservation has improved, and that observation of the roost containing educates the public about the environment. Observation of the visual scene created by the roost containing the swallows was found to contribute to improving awareness regarding the conservation of swallows in Kanagawa Prefecture.