IN GERMANY MANY CITIES ARE FACING A PROBLEM OF DECREASE OF HOUSING FUNCTION IN URBAN CENTRAL AREAS. THIS ARTICLE AIMS TO CLARIFY THE PLANNING SYSTEM FOR PROTECTION OF URBAN HOUSING IN GERMANY. AFTER EXAMINING THE PRESENT PLANNING INSTRUMENTS IN URBAN PLANNING LAW (BAUGESETZBUCH) SYSTEM, THE CASES OF HAMBURG AND DüSSELDORF ARE TREATED. THE BACKGROUND, PURPOSE AND LOGIC OF DISTRICT PLAN (BEBAUUNGSPLAN) FOR THE PROTECTION OF URBAN HOUSING IN BOTH CITIES ARE ANALYZED. IN BOTH CITIES, USING REGULATIONS OF BUILDING USE CODE (BAUNUTZUNGSVERODNUG), IT IS AIMED TO SECURE HOUSING USE ON UPPER FLOORS OF EXISTING BUILDINGS. IN THE PLAN MAKING PROCESS OF DISTRICT PLAN THE EXPLANATION REPORT, WHICH DESCRIBES THE REASON OF PLANNING REGULATION, IS IMPORTANT TO GET CONSENSUS FOR CITIZENS. THIS GIVES A HINT FOR PLANNING ADMINISTRATION IN JAPAN.