Respiratory muscle training is one of the major methods for enhancing the vocal function. Singers who must use their voice most frequently are well aware of the importance of respiration. However, most of them do not know precisely how to exercise their abdominal respiration. Using a respiratory training device, singers are expected to gain more efficiency in their vocal enhancement. The aim of the study was to examine the pulmonary function, the maximum inspiratory pressure (MIP) and the maximum expiratory pressure (MEP), and the maximum phonation time (MPT) in five female voice-majors students after undergoing specially programmed respiratory muscle training for 2 months. All the voice-majors had an average of 4.8 years of formal classical voice training. A respiratory muscle training device (Ultrabreathe®), Tangent health Care Inc., England) was used to train the respiratory muscle. None of the pulmonary function test variables had changed after respiratory muscle training. However, the MIP, MEP, and MPT were significantly increased higher after the respiratory muscle training. This suggests that the specially programmed respiratory muscle training can improve the respiratory muscle strength and vocal function without increasing the pulmonary function.