This study is to diagnose causes of damage and defects on external walls of brick structures, focused on "Naju Noahn" Catholic Church of Modern Architectural Properties. The causes of crack and deflection are overloading, shortage strength of arch. Among those, main cause is cauesd by shortage strength of arch because center of arch is dislocated and skew back of arch is small angle. The causes of damage and elimination are weathering, plants of friction, freezing and thawing, durability decrement of material and attach defection. This defects and damage is caused by high-moisture that occurs in soil. The causes of discoloration are change of soil moisture and flimsy brickwork. These defects and damage are mainly occurred in coping of cornice, weathering of window sill.
