In order to evaluate the magnetic field (MF) exposure level in residential areas near high voltage power lines, this research measured MF levels at 120 sites near high voltage transmission lines in the Busan region, Gwangju region, Daegu region and Changwon region from July to December, 2005, and compared and analyzed the efficiencies by measuring and applying the MF emission levels of underground cables and high voltage transmission lines. As a result of the investigation of the MF exposure level by the building usage, the average MF level of 17 locations at schools was $2.44{pm}2.45mG;$ that of 10 locations at hospitals $6.21{pm}12.39mG;$that of 76 locations at apartments $2.55{pm}2.98mG;$ and that at kindergartens and infant houses $3.32{pm}4.21mG$. MF exposure was analysed as a function of distance from the source and the MF levels directly below a source were $5.15{pm}8.72mG$, those within 30 m were $3.10{pm}3.32mG$, while those within 50 m were $2.45{pm}2.38mG$, and within 100 m were $0.71{pm}0.93mG$. In order to determine the difference of MF levels by the actual distance from high voltage transmission line within the same building, the evaluation of the floor position and the MF level has shown that the MF levels were highest in the order of roof, 4th floor, 3rd floor, 2nd floor and 1st floor. Comparison of MF emission intensity of underground cables and high voltage transmission lines, has shown that underground cables have an 86-94% of reduction ratio in MF compared to high voltage transmission lines, thus demonstrating higher efficiency.