A 41-year-old woman, presented with sore throat and dyspnea of 1 week’s duration. Fiberoptic laryngoscopy showed a swollen edematous epiglottis. Because the patient developed stridor and shortness of breath, tracheostomy was performed to secure the airway. Contrast-enhanced computed tomography (CT) showed high-density areas in the epiglottis, base of the tongue, and aryepiglottic folds. The patient was positive for proteinase 3 (PR3)-antineutrophil cytoplasmic antibody (ANCA, 4.9 U/ml) and negative for myeloperoxidase (MPO)-ANCA. A histo-pathological examination of an epiglottis biopsy specimen showed geographic necrotizing granuloma with a few scattered multinucleated giant cells. Transmural inflammation, luminal occlusion, and vessel disruption were observed on elastic staining. Based on these findings, the patient was diagnosed with granulomatosis with polyangiitis (GPA). Two months after the patient started therapy with high-dose steroids and cyclophosphamide, the epiglottic swelling improved. The level of PR3-ANCA returned to the normal range two months after starting treatment. Subglottic stenosis is reportedly a common clinical feature of GPA. Although the involvement of supraglottic structures, including the epiglottis, is rare in GPA, clinicians should include GPA in the differential diagnosis of a life-threatening airway obstruction.