We reported a case of MPS IV A presented with dyspnea on exertion and respiratory muscle weakness. The patient underwent inspiratory muscle training (IMT) using threshold loading for 18 weeks. After 6 weeks of initial IMT, aerobic exercise training consisting of walking was added to the treatment program. Inspiratory muscle strength increased 70%, and 6-minute walk test (6MWT) distance increased to 47 m. With the inclusion of aerobic exercise training, additional increases in inspiratory muscle strength (7%) and 6MWT distance (26.5 m) were obtained. Exertional dyspnea improved from severe to slight after 6 weeks of IMT, and to very slight after additional 12 weeks of combined aerobic training and IMT. Health-related quality of life improved especially in social function, emotional function, vitality, and physical role. In conclusion, inspiratory muscles can be trained with the improvement of muscle strength in a patient with Morquio's syndrome.