Purpose The purpose of this study was to evaluate the impacts of wearing a cosmetic corset during sitting and standing positions according to wearing time on lung capacity in healthy adults. Methods A total of 18 healthy adult women participated in the study. The spirometer was used to measure the forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), and maximum inspiratory pressure (MIP) in standing and sitting positions four times: before, immediately after, 30 minutes after, and 60 minutes after wearing the corsets. The oneway ANOVA was used to compare the differences in wearing the corset over time and the paired sample t test was conducted to compare the mean values according to different postures before and after wearing the corset. Results As a result, FVC, FEV1, and MIP all decreased during the comparison of mean values before and 60 minutes after wearing the corset. During the standing position, there was a significant difference in FVC and MIP (p<.05), but not in FEV1 (p>.05). For the sitting position, a significant difference was observed in FVC and FEV1 (p<.05), but not in MIP (p>.05). In addition, no significant difference was observed during the comparison between the standing and sitting position values (p>.05). Conclusion The findings of this study suggest that wearing a corset may negatively affect respiratory function by reducing lung capacity and may lead to an abnormal breathing pattern. Therefore, during exercise physical activities, it may be recommendable to avoid wearing corsets for a long time.