This study aimed to clarify predictors of depressive symptoms and anxiety symptoms after cancer diagnosis among Japanese cancer survivors (CSs). As part of a Japanese cancer survivorship research project commissioned by the Ministry of Health, Labour and Welfare (MHLW) of Japan, we conducted a web-based nationwide survey of CSs in 2018. We analyzed the risk factors for depressive and anxiety symptoms, as measured by the Hospital Anxiety and Depression Scale Japanese version (HADS). Of 1,234 Japanese CSs, mean score of HADS-depression and HADS-anxiety were 4.08 and 4.78, respectively. At the time of the study, the number of CSs with symptoms of depression and anxiety were 111 (9.0%) and 269 (21.8%), respectively. After multivariable analysis, CSs ≥ 60 years old (reference: ≤ 39 years old, odds ratios (OR): 0.39, 95%CI: 0.17-0.90) and those ≥ 10 years from cancer diagnosis (reference: 0-4 years, OR: 0.55, 95%CI: 0.32-0.96) had lower odds for depressive symptoms. And CSs ≥ 60 years old (reference: ≤ 39 years old, OR: 0.27, 95%CI: 0.15-0.49) and those ≥ 10 years from cancer diagnosis (reference: 0-4 years, OR: 0.62, 95%CI: 0.42-0.90) also had lower odds for anxiety symptoms. CSs who received chemotherapy (OR: 1.56, 95%CI: 1.10-2.20) had higher odds for anxiety symptoms. Based on manifestation of symptoms, CSs who were younger, closer to the time of cancer diagnosis, had advanced-staged cancer, or received chemotherapy may be at higher risk for depressive or anxiety symptoms. Those CSs who have higher risk for depression and anxiety symptoms, should be followed-up more carefully for better cancer survivorship, by medical professionals, companies, and society.