As concerns about dementia patients increase gradually in society, the nursing of them becomes more and more important. For intervening in dementia patients effectively, the most fundamental thing is to understand their characteristics and to increase the ability of assessing them. The assessment data supply us with the foundations of Nursing diagnosis and nursing plan. The reaseons why the assessment data are especially important to dementia patients are as follows; First, dementia patients have great differences among them in intellectual, physical ability. And their condition varies from time to time. Second, the intervention without planning results in the deficiency of consistence, and it rather embarrasses and makes dementia patients uneasy. Third, nursing of dementia patients requires participation of multi-disciplinary team because of characteristics of that disease. The development of an unitary assessment tool is essential for all members of the team to have close relations between them and care for dementia patients. Fully understanding the importance of assessment data, this study investigate the content to be included in the assessment before developing assessment tools to be used in community. It points out that the assessment should include the informations about patients, their family, and main care-giver. And it sets up items that can supply with detailed information on each person. In the future it is necessary to transform the contents of this study to more concrete items and develope the assessment tools for dementia patients. And recording paper for follow up should be supplemented to check any changes in family caring for dementia patients and describe the changes in detail. To make assessment tools is one of the fundamental works in controlling dementia patients. Therefore the official assessment tools should be provided as soon as possible. This study aimed at presenting the guiding principles for developing that assessment tools.