The present invention relates to a positive active material for lithium secondary battery, its manufacturing method, and lithium secondary battery including the same, and it provides that a positive active material for lithium secondary battery, comprising: a core and a coating layer, wherein, the core is lithium metal oxide, the coating layer comprises boron, the boron compound in the coating layer comprises a lithium boron oxide and a boron oxide, the lithium boron oxide is included 70 wt % or more and 99 wt % in the entire coating layer, the lithium boron oxide comprises Li2B4O7, with respect to the lithium boron oxide 100 wt %, the content of Li2B4O7 is 55 wt % or more and 99 wt % or less.