A negative electrode active material includes a silicon-based alloy represented by Si-M1-M2-C—B, wherein M1 and M2 are different from each other and are each independently selected from magnesium, aluminum, titanium, vanadium, chromium, iron, cobalt, nickel, copper, zinc, gallium, germanium, manganese, yttrium, zirconium, niobium, molybdenum, silver, tin, tantalum, and tungsten. In the silicon-based alloy, Si is in a range of about 50 at % to about 90 at %, M1 is in a range of about 10 at % to about 50 atom %, and M2 is in a range of 0 at % to about 10 at %, based on a total number of Si, M1, and M2 atoms. C is in a range of about 0.01 to about 30 parts by weight, and B is in a range of 0 to about 5 parts by weight, based on a total of 100 parts by weight of Si, M1, and M2.