Background/Aims: The ABC Dementia Scale (ABC-DS), a new tool for evaluating dementia, was developed in Japan. The ABC-DS is a comprehensive instrument that can simultaneously evaluate activities of daily living (ADLs), behavioral and psychological symptoms of dementia (BPSD), and cognitive function. The ABC-DS can be administered easily and quickly and can clarify the severity of dementia and its changes over time. While the ABC-DS has been reported to be useful in Alzheimer disease (AD)-type dementia, it has not yet been studied in other types of dementia. The purpose of this study was to reevaluate the standard validity of ABC-DS separately for various dementia types and severities. Methods: We evaluated the ABC-DS in outpatients at 1 hospital in Nagasaki Prefecture and patients who use the facility. Domain A, corresponding to ADLs, correlated with Disability Assessment for Dementia (DAD); domain B, corresponding to BPSD, correlated with the Neuropsychiatric Inventory (NPI); domain C, corresponding to cognitive functions, correlated with Mini-Mental State Examination (MMSE); and the total score of the ABC-DS correlated with the Clinical Dementia Rating (CDR). Results: 102 patients, comprising 38 males and 64 females with an average age of 80.7 ± 8.6 years, were enrolled. AD-type dementia was present in 38 cases, vascular dementia (VaD) in 23, mixed dementia in 23, dementia with Lewy bodies in 6, argyrophilic grain dementia in 9, and mild cognitive impairment in 3. A strong correlation was found between ABC-DS domain scores and their respective reference neuropsychological instruments (domain A and the DAD, domain B and the NPI, domain C and the MMSE, and total score and CDR). The correlation of each ABC-DS domain score with the corresponding standard scale depended on the type and severity of dementia, and we observed moderate or high correlations in AD and VaD patients with moderate and severe dementia. Discussion: Although the ABC-DS targets AD, it can be used in VaD based on the results of this study. In other types of dementia, the results differed depending on the domain; in some conditions, the ABC-DS may not show sufficient concurrent validity with other standard scales. Also, the ABC-DS is more beneficial for moderate-to-severe dementia, as reported in previous studies. It is highly useful in clinical practice in Japan since there more than half of all patients have moderate-to-severe dementia.