In Lake Biwa basin, various citizens' activities are being promoted for sustainable society based on the Mother Lake Goals (MLGs). This study aimed to clarify the factors affecting factors affecting the attachment to the lake and residential area to those citizens’ activities. The questionnaire survey was conducted for Shiga prefectural residents, and the obtained data were analyzed by covariance structure model. As a results, attachment to lake and the residential area affected on the willingness to act for MLGs directly. On the other hand, the attachment influenced the actual behavior through the interest in lake basin environmental conservation indirectly.