Weeks who is an architect in England suggest that let us consider the hospital architecture as not determined architecture but an undetermined architecture. Because it has been changing unexpectedly. The changing process of hospital architecture is required that it has to involve the new function and be a role model because of variations of environmental factors. For silving the requirements above mentioned, hospital architecture takes the way of appropriateness inner origin form and finally it considers new formation. The 53% of hospital buildings in Korea were built in 1980s. For 30years, these buildings have been not only extended a buildings but also changed in parts of functions and sizes on buildings which are original. The purpose of this study is producing the basic references which suggest solution to face on the changing of hospital building during planning it in the future using by analysis of variation inside the hospital building and grasping of characters in each departments. Each department is analyzed as follows. There is no inner change but only expansion partly by enlargement of building. In the outpatient, there is not only expansion by enlargement of building and but also extension toward other parts and the rate of variation of inside is high. In the diagnostic treatment, there are differences in diagnostic treatment. Surgical suit and diagnostic imaging have been expanded by enlargement than the change of inside. But the others of the departments have been changed by change of inside and also there are sometimes changes of inner walls.