The aim of this study was to investigate the dementia provision for elderly cancer patients in designated regional cancer centers. A survey was mailed to 389 designated regional cancer centers from February to June, 2015. A total of 188 facilities responded (response rate: 48.3%). 5.3% of the respondents used two manuals (on basic dementia care and the behavioral and psychological symptoms of dementia) to check whether these centers were following appropriate measures. About 50% of the respondents performed dementia assessments by the primary care team. 29.3% of the respondents maintained the system of the education and training of dementia care. Therefore, dementia provision for elderly cancer patients in designated regional cancer centers needs to improve the education of dementia care.