Lung cancer is the leading cause of death from cancer in Japan. Studies in other countries have reported a venous thromboembolism (VTE) rate of 4%–20% in cancer patients. In this study, we aimed to determine the incidence of VTE in lung cancer patients in Japan and compared the characteristics of patients with and without VTE. In this retrospective cohort study, the clinicopathological characteristics of study patients with and without concomitant VTE were compared. Patients with lung cancer treated at Fukui Prefectural Hospital, Japan from 2008 to 2017. Of the 1471 patients with lung cancer studied, 28 developed VTE. Five patients developed pulmonary thromboembolism (PTE) alone, 9 PTE with concomitant deep vein thrombosis, and 14 deep vein thrombosis alone. Compared with patients in the non-VTE group, the VTE group was significantly younger (mean value ± SD 66.3 ± 10.1 vs. 73.0 ± 10.6 years, p = 0.001), contained significantly more patients with stage IIIb–IV disease (p = 0.002), and had a significantly higher rate of chemotherapy (p < 0.001) and radiation therapy (p = 0.007). There was no significant difference in median survival time from lung cancer diagnosis between the VTE and non-VTE groups. The 1-year mortality rate after VTE diagnosis was 60.7%. Lung cancer was the most frequent cause of death, followed by infection and VTE. Several baseline characteristics differed between patients with and without VTE. The prognosis may worsen after development of VTE, suggesting that lung cancer patients should be carefully monitored for it.