We examined whether preoperative inspiratory muscle weakness (IMW) is a risk factor for postoperative pulmonary complications (PPCs) in patients with esophageal cancer who underwent subtotal esophagectomy. This single-center retrospective cohort study enrolled patients with esophageal cancer who underwent a scheduled subtotal esophagectomy between June 2020 and May 2022. Maximal inspiratory pressure (MIP) was measured as inspiratory muscle strength using a respiratory dynamometer, and we defined IMW as MIP < 80% of the predicted value. Our primary outcome comprised overall PPCs. We investigated the relationship between IMW and PPCs using the Bayesian logistic regression model. After exclusion, 72 patients were included in this study. IMW was identified in 26 patients (36%), and PPCs developed in 28 patients (39%). Among patients with IMW, 15 (58%) developed PPCs. Preoperative IMW was associated with PPCs (mean odds ratio [OR]: 3.58; 95% credible interval [95% CrI]: 1.29, 9.73) in the unweighted model. A similar association was observed in the weighted model adjusted for preoperative and intraoperative contributing factors (mean OR: 4.15; 95% CrI: 2.04, 8.45). Preoperative IMW was associated with PPCs in patients with esophageal cancer who underwent subtotal esophagectomy. This association remained after adjusting for preoperative and intraoperative contributing factors.