Most people with dementia remain living at home as long as possible after being diagnosed, and hence their lives also include activities in the public space. The aim of this study was to illuminate experiences of accessibility in public space in people with Alzheimer’s disease. A qualitative grounded theory approach with repeated in-depth interviews was used. The core category, accessibility as a constantly changing experience, was characterized by changes in the relationship between informants and public space. Changes in the relationship took place in activities and use of place and related to familiarity and comfort, individual motives and interests, and planning and protecting. Other changes occurred in places and problematic situations related to everyday technologies, crowded places with high tempo and noise, and change of landmarks. These changes reduced feelings of accessibility and increased difficulties in carrying out activities in public space. These findings may be helpful when providing support, and supporting community living.