Background: We examined the association between caregiver burden and work productivity (i.e., absenteeism, presenteeism, and overall work impairment) among working family caregivers of people with dementia and whether job characteristics (i.e., job demands, job control, supervisor and coworker support) moderate this association.; Methods: A cross-sectional correlational study design using a web-based questionnaire survey was conducted among 379 Japanese working family caregivers of people with dementia (105 female, age range 20-77) in May 2016, which measured caregiver burden, work productivity, care situation, job characteristics, and demographics. Caregiver burden was designated as an independent variable and each aspect of work productivity as a dependent variable in a hierarchical multiple regression analysis, adjusting for demographics. Interaction terms between caregiver burden and each job characteristic were also included in the model.; Results: Caregiver burden was significantly and positively associated with presenteeism (β = 0.219, p < 0.001) and overall work impairment (β = 0.181, p < 0.001), while the association of caregiver burden with absenteeism was not significant (β = - 0.003, p = 0.953). Interaction effects of caregiver burden × coworker support on presenteeism (β = - 0.189, p = 0.023) and overall work impairment (β = - 0.172, p = 0.034) were significant. According to simple slope analyses, caregiver burden was greater at lower levels of coworker support compared to higher levels of coworker support for both presenteeism and overall work impairment.; Conclusions: Our study suggests that higher caregiver burden is associated with a decrease in work productivity. Additionally, coworker support appears to buffer the association of caregiver burden with presenteeism and overall work impairment among working family caregivers of people with dementia.