As awareness of environmental concerns continues to grow, sustainable fashion has emerged as a significant global issue. This study classified sustainable fashion advertisements into positive and negative message types and analyzed their effect on brainwaves. The study featured 38 female participants with an average age of 22 years. Participants’ brainwaves were monitored as they watched four fashion ads, which were then followed by a survey. The data gathered from the brainwave monitor was analyzed using SPSS 26.0. Stabilized brainwaves in advertising message types showed differences in Beta L, prefrontal asymmetry in Gamma waves, and AF3/AF4 activation differences in the left hemisphere. For advertising attitude, purchase intention, and sustainability evaluation, stabilized brainwaves showed differences in Alpha, Beta H, Beta L, and Gamma waves, with prefrontal asymmetry and AF3/AF4 activation, primarily in the left hemisphere. The effect of advertising message types on purchase intention and sustainability evaluation was partially supported. The significance of this study lies in the empirical analysis of the effect of fashion advertisement messaging using neuroscientific methods. These findings contribute to the development of effective advertising communication strategies and provide theoretical and practical implications for the ongoing evolution of marketing strategies in sustainable fashion.