Provided are an anode active material including a porous silicon oxide-carbon material composite which includes a porous silicon oxide including pores and a line-type carbon material coated on a surface, in the pores, or on the surface and in the pores of the porous silicon oxide, and a method of preparing the anode active material.Since the silicon oxide of the anode active material according to an embodiment of the present invention may include the plurality of pores, resistance to the mechanical stress due to a volume change may be improved. Also, since the line-type carbon material is bonded to the inside of the pores, conductivity may not be decreased even in the case in which internal cracks occur in the porous silicon oxide and lifetime characteristics may be improved.