Background: A number of retrospective studies reported that 5-year survival rate was 30-60% in patients who underwent curative resection of pulmonary metastases (PM) from colorectal cancer (CRC), and PM-CRC resection was recommended in clinical practice. Efficacy of adjuvant chemotherapy after resection of PM remains unclear. Therefore, using a large-scale data obtained from patients who underwent R0 resection of PM in Japan, we investigated it with a propensity score-matching analysis. Methods: We retrospectively collected clinical data of 1237 patients who underwent metastasectomy of PM-CRC at 46 Japanese institutions from 2004 to 2008. Excluding non-curative resection, preoperative chemotherapies, extra-thoratic metastases, complications after surgery, and inadequate data, 530 patients’ data (surgery alone 269 and surgery with adjuvant chemotherapy 261) were used for the matching. Patient backgrounds affecting doctor’s recommendation of adjuvant chemotherapy and including commonly reported prognostic factors were adjusted, using a propensity score-matching method. Primary and secondary endpoints were overall survival (OS) and disease-free survival (DFS), respectively. Results: After the matching with propensity-score, 167 patients for each group were selected. Patient backgrounds were balanced between both groups. Adjuvant chemotherapies were fluorouracil alone (67%), oxaliplatine-containing regimen (24%), irinotecan-containing regimen (7%) and others (2%). There were no significant differences between both groups in OS (HR 0.97, 95%CI 0.64-1.46, p = 0.88) and DFS (HR 0.99, 95%CI 0.75-1.32, p = 0.96). Conclusions: A propensity score-matching analysis did not show a survival benefit of adjuvant chemotherapy after resection of PM in patients with CRC. A large prospective observational study with high quality or randomized clinical trial is needed.