Negative active material for rechargeable lithium battery and rechargeable lithium battery including the same

Disclosed are a negative active material for a rechargeable lithium battery and a rechargeable lithium battery including the same. The active material includes an amorphous silicon-containing compound represented by the following Chemical Formula 1. SiC [Chemical Formula 1] wherein, 0.05 ≤ x ≤ 1.5.