INTRODUCTION: In order to clarify the optimal strategy regarding conversion surgery (CS) for gastric cancer (GC) patients, we focused on clinicopathological findings, including immunological factors, related to the favorable prognosis in patients with stage IV GC who underwent CS. MATERIALS AND METHODS: A total of 25 patients with Stage IV GC who underwent induction chemotherapy (IC) and CS at our hospital between 2010 and 2021 were enrolled in this study. Biopsy specimens before IC and surgical specimens were collected. Immunohistochemical staining was performed using programmed death-ligand 1 (PD-L1) antibody, translationally controlled tumor protein (TCTP) antibody, and CD20 antibody. Prognostic factors were investigated using clinicopathological factors as well as immunological factors such as PD-L1, TCTP, and CD20 expression. RESULTS: cN0, ycStage1-2, R0-1 surgery, D2 lymph node dissection, ypN0, and ypStage1-2 were significantly associated with favorable overall survival. Among patients who underwent R0/1 surgery, only histological type was a significant prognostic factor for recurrence-free survival. Low PD-L1 expression before IC and high TCTP expression after IC were significantly associated with favorable recurrence-free survival. CONCLUSIONS: In addition to clinical factors, high TCTP expression after IC was identified as a significant favorable prognostic factor, which could help in identifying candidates for CS in the future.