One of the primary objectives of brand strategy is to foster consumer attachment to brands. Brand attachment refers to the combination of passionate brand-supporting behaviors exhibited by consumers satisfied with a specific brand and positive emotions arising from long-term relationship formation, and it has been recognized as a key construct in explaining the consumer-brand relationship formation process. This study focuses on brand attachment as a core element for maintaining and strengthening consumer brand loyalty in the case of high-involvement product brands such as PCs, laptops, and fashion apparel, and proposes brand image-consumer self-image congruence and brand trust as the primary sources in forming brand attachment. The study also analyzed the relative influence of these factors on brand attachment and the moderating effects according to product type. The empirical analysis results revealed that ideal self-image congruence had the greatest influence on brand attachment, followed by brand trust and actual self-image congruence, both of which exhibited positive effects on brand attachment. Moderating effects according to product type were also observed. For utilitarian products, actual self-image congruence and brand trust positively influenced brand attachment, while for hedonic products, ideal self-image congruence and brand trust positively influenced brand attachment, confirming the moderating role of product type. The implications of the empirical analysis suggest that in order to build brand attachment, firms must develop marketing communication strategies and programs that align consumers' ideal self-image and actual self-image with the brand image while enhancing brand credibility. Furthermore, it is necessary to differentiate marketing communication efforts for building brand attachment according to product type.