This paper discusses the concept of carrying capacity of tourist destination area and analyzes case studies for its optimal level. A rapid increase of tourist demand has given rise to great economic, social cost in comparison with its benefits from tourism. To promote quality of life both tourist destination populations and tourist, the concept of optimal carrying capacity is very important. But the calculation and control of carrying capacity has not been taken seriously by developers, whether public or private. This has resulted in many cases in overcapacity within the areas developed for tourism, causing the destruction or near-destruction of historical landmarks and even of the natural environment. Thus it is necessary for the concept of tourism carrying capacity to be included in the planning for tourism as initiated by governments and other developers, in spite of difficulties in measurement.