Objective Mortality analyses of patients with coronavirus disease 2019 (COVID-19) requiring invasive mechanical ventilation in Japan are limited. The present study therefore determined the risk factors for mortality in patients with COVID-19 requiring invasive mechanical ventilation. Methods This retrospective cohort study used the dataset from the Japanese multicenter research of COVID-19 by assembling real-word data (J-RECOVER) study that was conducted between January 1 and September 31, 2020. Independent risk factors associated with in-hospital mortality were evaluated using a multivariate logistic regression analysis. Kaplan-Meier estimates of the survival were calculated for different age groups. A subgroup analysis was performed to assess differences in survival rates according to additional risk factors, including an older age and chronic pulmonary disease. Patients A total of 561 patients were eligible. The median age was 67 (interquartile range: 56-75) years old, 442 (78.8%) were men, and 151 (26.9%) died in the hospital. Results Age, chronic pulmonary disease, and renal disease were significantly associated with in-hospital mortality. Compared with patients 18-54 years old, the adjusted odds ratios of patients 55-64, 65-74, and 75-94 years old were 3.34 (95% CI, 1.34-8.31), 7.07 (95% CI, 3.05-16.40), and 18.43 (95% CI, 7.94-42.78), respectively. Conclusion Age, chronic pulmonary disease, and renal disease were independently associated with mortality in patients with COVID-19 requiring invasive mechanical ventilation, and age was the most decisive indicator of a poor prognosis. Our results may aid in formulating treatment strategies and allocating healthcare resources.