The influence of pulmonary dysfunction on postoperative outcomes in older patients with gastric cancer was assessed. In this retrospective study, 352 older patients (age ≥ 75years) with gastric cancer who underwent preoperative spirometry and curative gastrectomy were enrolled. Of these patients, 200 underwent laparoscopic gastrectomy. Restrictive and obstructive pulmonary dysfunction were defined as percentage of vital capacity (%VC) < 80% and percent of forced expiratory volume in one second (FEV1.0%) < 70%, respectively. Twenty-six (7.3%) and 123 (34.9%) exhibited restrictive and obstructive pulmonary dysfunction, respectively. The low-%VC group showed a higher incidence of postoperative pneumonia (p = 0.018) while the low-FEV1.0% group did not (p = 0.677). Multivariate analysis identified a decreased %VC as a significant risk factor for postoperative pneumonia. However, this association was not observed in patients who underwent laparoscopic gastrectomy. Concerning the long-term outcomes, restrictive dysfunction was a significant prognostic factor in older patients with gastric cancer who underwent either laparotomy or laparoscopy, whereas obstructive dysfunction did not. Restrictive pulmonary dysfunction increased the risk of postoperative pneumonia and had a negative prognostic effect in older patients with gastric cancer, whereas obstructive pulmonary dysfunction did not.