Disclosed is active material for a positive electrode used in lithium secondary batteries of Formula 1 below and a method manufacturing the same, a surface of the active material being coated with metal oxide. The method includes the steps of producing a crystalline powder or a semi-crystalline powder of Formula 1; coating the crystalline powder or the semi-crystalline powder with metal alkoxide sol; and heat-treating the powder coated with the metal alkoxide sol.where 0<x<=0.3, 0<=y<=0.01, andA is an element selected from the group consisting of Ni, Co and Mn; B is an element selected from the group consisting of Ni, Co, Mn, B, Mg, Ca, Sr, Ba, Ti, V, Cr, Fe, Cu and Al; and C is an element selected from the group consisting of Ni, Co, Mn, B, Mg, Ca, Sr, Ba, Ti, V, Cr, Fe, Cu and Al.