Purpose: Accumulated evidence indicates laparoscopic surgery (LS) has the advantages of less wound pain, less blood loss, shorter hospitalization, and faster functional recovery than open surgery (OS). Previous studies have analyzed the advantages of LS based on hospital data. This study is the first to compare surgical outcomes and health economic data using nationwide administrative claims datasets for gastric cancer. Methods: The claims datasets of the Health Insurance Review and Assessment Service for patients that underwent gastrectomy from May 2012 to April 2017 were analyzed. A total of 76,445 cases (LS, 42,395 and OS, 34,050) were included.Postoperative complications and medical costs were included in the analysis. Results: We analyzed 76,445 cases of gastrectomy. Analysis showed LS was associated with fewer surgical wound infections (2,114 [6.21%] vs. 1,057 [2.49%], p < 0.001), minor abdominal infections and abscesses (826 [2.43%] vs. 390 [0.92%], p < 0.001), cases of surgery-related peritonitis (50 [0.15%] vs. 31 [0.07%], p = 0.0019), repair surgeries (28 [0.08%] vs. 3 [0.01%], p < 0.001), reoperations (504 [1.48%] vs. 343 [0.81%], p < 0.001), less antibiotic use (1,717 [5.04%] vs. 1,268 [2.99%], p < 0.001), and shorter hospital stays (13.61 days vs. 9.97 days, p < 0.001). However, average medical cost was 510,734 Korean Won (444 US dollar) higher for LS than OS. Conclusion The study confirms the clinical benefits of LS over OS for gastrectomy in terms of fewer postoperative complications and shorter hospital stays. However, the average medical cost of LS was higher than that of OS.