This study develops a quality of life instrument for older Japanese people experiencing dementia (QLDJ). Quality of life (QL) for these older adults is defined as a three dimensional construct including 1) interacting with surroundings, 2) expressing self, and 3) experiencing minimum negative behaviors. From 53 items in the initial item pool, 24 were selected based on item reliability and validity using data from 3 studies that involve ten dementia-care experts (Study A) and 36 and 623 older persons and their formal caregivers in various care settings (Study B & C). Factor analysis of these items identified three domains that correspond to the conceptual definition of QL for older adults with dementia. The domain and total QL scores were calculated considering the relative weights of each item. Resultant domain and total scores of the QLDJ showed satisfactory reliability and evidence of validity. (Contains 5 tables, 1 figure and 4 footnotes.)