The Myeongdongseongdang Cathedral, which was designated as Historic Site No. 258 in Korea, is a representative cathedral of Korean Catholic church designed by a French priest Eugene-Jean Georges Coste and completed in 1898. It is a Gothic-styled architecture constructed with bricks and stones. Lithological and mineralogical analyses determined that holy stone relics were made of marble and granite, and foundation stones are of pink feldspar granite. Deterioration mapping and ultrasonic measurement revealed main weathering and damage were exfoliation (40%) and black discoloration (37%) in the holy water basin, and exfoliation (6%) and discoloration (46%) in the exterior foundation stones. Ultrasonic velocity of the stones were calculated as 3,525m/s in the holy water basin and 2,795m/s in the exterior stones that indicated these stones were sorted into moderately to highly weathered rock. This was resulted from moisture and atmospheric pollutants around the cathedral.