The purpose of this study was to investigate the changes in the flexicurve kyphosis index (KI), the flexicurve lordosis index (LI) and the distance from the inferior angle of the scapula to the nearest vertebral spinous process (DS), as a dependent variable of scapular protraction, after applying of adolescents with thoracic hyperkyphosis using three different garments. A repeated measures design was used. Ten adolescents ($15.8{pm}1.0$ years) with thoracic hyperkyphosis ($40.1{pm}3.7$ Cobb angle) were recruited from a university hospital. A flexicurve ruler was used to measure KI and LI and a scoliometer was used to measure DS under three different conditions: wearing-a hospital garment (HG), wearing-a sham garment (SG), and wearing-an experimental garment (EG). KI under EG condition was significantly decreased compared with that wearing the HG. However, there was no significant difference between wearing the SG and HG. LI when wearing the EG was significantly increased compared with that when wearing HG. However, there was no significant difference under SG and HG conditions. DS when wearing the EG was significantly decreased compared with wearing HG. However, there was no significant difference between the SG and HG. The results of this study show that the EG was effective in decreasing KI, but not effective in decreasing LI. Hence, the effect of the EG for correcting sagittal spine angle in adolescents with thoracic hyperkyphosis is still debatable. However, since we showed that DS decreases in the EG, this method could be applied in correcting the scapular protraction.