The purpose of this current study is to analyze the pattern of wondering behavior of an elderly person with severe dementia, and to evaluate the impact of actions taken by the care staff on the person's behavior. This research was conducted in a nursing home in Shimabara, Nagasaki Prefecture. The subject of this study was one elderly woman, 77 years old, with severe dementia (5 points on the NM scale; 15 points on the N-ADL). Her behavior in daily life was video taped 6 times a day (10 minutes per time) over 3 consecutive days for three months. A total of 162 minutes data, during which the subject stayed in the living room, was analyzed. The video data, processed point- and one-zero-sampling methods, showed daily activities, interpersonal behaviors, and received care by the staff members. The subject sat strait on Tatami for 31.3% of the total observation time, sat on a chair for 29.9%, and much of the remaining time the subject wondered around the living room. Ninety-three percent of the sitting bouts (from sitting down to the uprising) were less than 60 seconds. The average duration of the sitting bouts was 29.4 seconds, and the average interval time between sitting bouts was 25.2 seconds. When the subject was lead to sit or forced to sit, the subject showed significantly more gross body movements than when the subject sat by free will. While sitting, the subject displayed many involuntary jerking movements, which appeared to be an expression of discomfort. Wondering, thus, appeared to provide this elderly person with dementia some degree of internal comfort; when the care staff retrained her from wandering, she displayed agitated behavior suggesting that the optimal treatment for this subject would involve minimal restraint on her movement.