PURPOSE: Air leakage is a common complication of lung surgery that sometimes requires medical intervention and leads to a prolonged hospital stay. This study assessed the risk factors associated with air leakage following anatomical pulmonary resection. METHODS: We retrospectively analyzed 194 patients who underwent anatomical pulmonary resection in 2020. A risk factor analysis was performed separately for intraoperative air leakage (IAL) and postoperative air leakage (PAL) by examining patient characteristics and operative findings. RESULTS: Of 194 patients, IAL was observed in 94 (48.4%). The number of staplers used for pulmonary resection and Brinkman index were significantly higher in the IAL group than in the non-IAL group (3.2 vs. 2.5, p = 0.005 and 696.2 vs. 477.1, p = 0.013, respectively). PAL was observed in 40 (20.6%) patients (25 IAL and 15 non-IAL patients). There were more lobectomy cases in the PAL group than in the non-PAL group (77.5 vs 60.4%, p = 0.0447). Pleurodesis was performed in 18 (45%) patients in the PAL group. CONCLUSION: The risk factors differed between IAL and PAL. Since most PAL cases involve the IAL, and approximately half of the PAL cases require pleurodesis, attention should be paid to PAL prevention, especially during stapling procedures in the lung parenchyma.