Background: Individuals with forward head posture (FHP) have neck pain. To correct the FHP, a posture correction band is commonly used. However, we do not know the posture correction band influenced the pulmonary function in individuals with FHP. Objects: This study aimed to elucidate the effects of the posture correction band on the pulmonary function in young adults with neck pain and FHP and to monitor how the pulmonary function changed over time. Methods: Twenty subjects with chronic neck pain and forward head posture were recruited. Subjects performed pulmonary function test four times: before, immediately, and 2 hours after wearing the postural band, and immediately after undressing the postural band. Vital capacity (VC), forced vital capacity (FVC), peak expiratory flow (PEF), and forced expiratory volume at one second (FEV1) were measured. The modified Borg dyspnea scale was used to measure each subject’s responses to the posture correction band. The mixed-effect linear regression was used to the effect of the posture correction band over time. Results: There were no significant differences in VC, FVC, PEF, FEV1 values over time (p > 0.05), although all values slightly decreased after applying posture correction band. However, the score of the modified Borg scale significantly changed after wearing the postural bands (p < 0.05), indicating the subject felt discomfort with posture correction band during breathing. Conclusion: Because the posture correction band did not change the pulmonary function over time, but it induces psychological discomforts during breathing in people with FHP. Therefore, this posture correction band can be used for FHP realignment after discussion with the subjects.