An organometallic complex for an organic light emitting device represented by formula 1, a method of preparing the same and an organic light emitting device including the same: where R1 through R16 are a hydrogen atom, a cyano group, a hydroxyl group, a nitro group, a halogen atom, a C1-C20 alkyl group, a C1-C20 alkoxy group, a C6-C20 aryl group, a C7-C20 arylalkyl group, a C2-C20 alkylalkoxy group, a C7-C20 arylalkoxy group, a C6-C20 arylamino group, a C1-C20 alkylamino group, a C6-C20 heteroarylamino group, and a C2-C20 hetero-ring group; and M is a bivalent metal such as Be, Mg, Zn, Ca, Cr, Fe, Co, Ni and Cu. The compound represented by Formula 1 can be effectively used in an electron transport layer or an electron injection layer. An organic light emitting device including the compound represented by Formula 1 can thus have long lifetime.