Background Dysphagia is a prominent symptom after esophagectomy and may cause aspiration pneumonia. Swallowing evaluation after esophagectomy can predict and help control the incidence of postoperative pneumonia. The aim of this study was to clarify whether the change in tongue pressure was associated with any related factor and postoperative dysphagia/pneumonia in patients with esophageal cancer after esophagectomy. Methods Fifty-nine inpatients (41 males and 18 females; 33-77 years old) who underwent esophagectomy participated in this study. Measurement of tongue pressure and the repetitive saliva swallowing test (RSST) was performed before esophagectomy (baseline) and at 2 weeks postoperatively. The general data were collected from patients' medical records, including sex, age, type of cancer, cancer stage, location of cancer, operative approach, history of previous chemotherapy, surgical duration, amount of bleeding during surgery, incidences of postoperative complications, intubation period, period between surgery and initiation of oral alimentation, and intensive care unit (ICU) stay, blood chemical analysis, and lifestyle. Results Tongue pressure decreased significantly after esophagectomy (p = 0.011). The decrease of tongue pressure was significantly associated with length of ICU stay and preoperative tongue pressure on multiple regression analysis (p < 0.05). The decrease of tongue pressure in the RSST<3 or postoperative pneumonia (+) group was significantly greater than in the RSST≥3 (p = 0.003) or pneumonia (-) group (p = 0.021). Conclusions The decrease in tongue pressure was significantly associated with the length of ICU stay, preoperative tongue pressure, and the incidence of dysphagia and pneumonia among inpatient after esophagectomy.