Lecanora muralis was found on the rock along coastal line during the field trip in Jeju island in 2006. Thallus crustose, placodioid, closely adnate, forming orbicular patches; upper surface grayish green, glossy; central lobes areolate, marginal parts plane, edges thin pruinose; lower surface ecorticate; apothecia sessile, lecanorine type, exciple dense and intact when young, and disc plane, but when mature, exciple laciniate, disc protrudent, yellowish brown to orange, $0.5{sim}1.5$ mm in diameter; ascospores ellipsoid, simple, colorless, $12.5{sim}15.0{ imes}5.0{sim}7.5;{mu}m$. Usnic acid and zeorin contained in thallus. This is the first record of this species in South Korea.