A 34-year-old pregnant woman in the 34th week of gestation with uncontrolled asthma was admitted because of asthma exacerbation. Although she received bronchodilators and systemic corticosteroids, respiratory failure rapidly progressed. Chest computed tomography revealed a mass occluding approximately 80% of the tracheal lumen. After urgent Caesarean section, endobronchial resection was performed. The pathological findings of the resected tumor were compatible with tracheal glomus tumor. Tracheal tumors are often misdiagnosed as asthma, but its complication with asthma is rare. Even if the diagnosis of asthma is definitive, clinicians should consider coexisting diseases, including tracheal tumors, when asthma control is poor.