This paper proposes a novel method to alleviate motion sickness symptoms using AI-based brain-computer interface (BCI). We developed a BCI system that integrates tasks such as breathing training and conducted an experiment with 43 participants in an actual ship environment. As a result of the experiment, 81.39% of the participants reported that the BCI intervention was effective, and the EEG analysis results confirmed that motion sickness-related brain wave patterns were regulated, such as a decrease in the overall power of the brain waves, an increase in the relative power of theta waves, and a decrease in the relative power of beta waves. In particular, the theta/beta ratio, an attention index, significantly decreased during the actual feedback session, supporting the attention shift effect through BCI. This study suggests a portable, effective non-drug treatment for motion sickness and suggests a new application field of BCI.