This study aimed to identify sub-dimensions of the authenticity and fictionality of a brand story and analyze the effects of authenticity and fictionality on customer-based brand equity. Data were obtained from a group of 213 males and females in their 20s and 30s living in Korea using an online survey institute. Results showed that the authenticity and fictionality of a brand story are composed of reality, excitement, exaggeration, fictional symbolism, influence, sincerity, relativeness, mysteriousness, and unreality. Of these, sincerity, excitement, reality, influence, and mysteriousness had significant effects on brand imagery; sincerity particularly exerted a relatively more substantial influence on brand imagery. Also, influence, mysteriousness, excitement, and relativeness impacted performance positively, and exaggeration impacted performance negatively. This indicated that a well-constructed brand story with authenticity and fictionality had a positive impact on the brand image. Excitement, mysteriousness, reality, relativeness, sincerity, and influence of a brand story had significant effects on brand judgement. In contrast, only excitement and influence positively impacted brand feelings, and unreality had a negative impact on feelings. The exciting and influential brand story impacted brand attitude. Also, brand image and attitude positively impacted sharing and purchase intention, while brand performance did not affect recommendation intention. These findings contribute to identifying a brand story’s attributes, authenticity, and fictionality and provide insights for marketers on creating brand stories to increase brand image and attitude and to build customer-based brand equity.