This study investigates effect of the soundproof wall installed along the roadside of Pusan metropolis. Eight soundproof walls of heavy traffic road have been selected among the total 30 walls in Pusan. Repeated noise measurement during the daytime and nighttime have been implemented to compare the equivalent sound level of the front with the back of the soundproof wall. Result are as follows; First, daytime noise intensity at the back of the soundproof wall was 9.89(8.50∼11.28)dB SPL less than that of the front of the wall. Second, nighttime noise intensity at the back of the soundproof wall was 4.66(0.73∼6.45)dB SPL less than that of the front of the wall. Third, noise reducing effect of soundproof of the daytime is greater than the nighttime.