A door of radiation therapy room needs enough shielding ability. However, radiation therapy room needs quick enter for safety of patients. Therefore, To evaluate the shielding ability and stability of each room construction, door format, and control button position. Material is 8 room construction, 6 door format, and 3 control button position. It was compared time and leakage dose according to each type. The hinged door type with handle was best of patients stability, and the sliding door type was best of shielding ability. It is considered necessary, standard on the provision of door format and position of control button about each construction of radiation therapy room.