The purpose of the study was to investigate and analyze the relationships among four research variables: participation motivation, event attachment, sponsor's brand image and participants' behavioral intention. This study used on-site convenience sampling. Survey questionnaires were administered to 297 people who had personally participated in the Fubon Taipei International Marathon. The study then used structural equation modeling to run path analysis. The results showed that: (1) participation motivation had an effect on event attachment and sponsor's brand image, (2) event attachment had an effect on participants' behavioral intention, and (3) sponsor's brand image had an effect on participants' behavioral intention. The study found that participation motivation influenced event attachment directly and influenced behavioral intention indirectly. The total effect of the attachment-behavioral intention path was greater than the total effect of the brand image-behavioral intention path. It is suggested that only long-term sponsorship of charity sport events would create the event attachment necessary to influence customers' behavioral intention.