Dementia is a major public health concern in ageing societies. Although the population of Japan is among the most aged worldwide, long-term trends in the place of death (PoD) among patients with dementia is unknown. In this Japanese nationwide observational study, we analysed trends in PoD using the data of patients with dementia who were aged ≥65 years and died during 1999-2016. Trends in the crude death rates and PoD frequencies were analysed using the Joinpoint regression model. Changes in these trends were assessed using the Joinpoint regression analysis in which significant change points, the annual percentage change (APC) and average APCs (AAPC) in hospitals, homes, or nursing homes were estimated. During 1999-2016, the number of deaths among patients with dementia increased from 3,235 to 23,757 (total: 182,000). A trend analysis revealed increased mortality rates, with an AAPC of 8.2% among men and 9.3% among women. Most patients with dementia died in the hospital, although the prevalence of hospital deaths decreased (AAPC: -1.0%). Moreover, the prevalence of nursing home deaths increased (AAPC: 5.6%), whereas the prevalence of home deaths decreased (AAPC: -5.8%). These findings support a reconsideration of the end-of-life care provided to patients with dementia.