Abstract: Provided is a negative active material for a secondary battery which provides high capacity, high efficiency charging-discharging characteristics. The negative active material includes: a silicon single phase; and a silicon-metal alloy phase interfaced with the silicon single phase and surrounding the silicon single phase, wherein an X-ray diffraction spectrum of the negative active material has first and second peaks that are originated from the silicon-metal alloy phase, and the first peak is located at 49.1+/?0.5 degrees (°) and the second peak is located at 38.0+/?0.5 degrees (°), and a diffraction intensity of the first peak is 2 or less times that of to the second peak.