Coprinus comatus, also called chicken drumstick mushroom, is currently commercially available in China. Hot water and ethanolic extracts were prepared from cap and stipe of C. comatus fruit bodies and their antioxidant properties were studied. Ethanolic extract from stipe showed high antioxidant activity (80.6%) at 1 mg/mL. Reducing power of hot water extracts from cap was 1.653 at 10 mg/mL. Extracts from cap showed better scavenging ability on DPPH (57.9% at 1 mg/mL) than stipe ones. Ethanolic extracts were more effective in scavenging ability on hydroxyl radicals (57.4–61.3% at 5 mg/mL) than hot water extracts. Ethanolic extracts showed moderate scavenging ability on superoxide radicals (46.3–47.0% at 20 mg/mL). Naturally occurring antioxidant components including total phenols (3.60–20.00 mg/g), tocopherols (0.58–11.93 mg/g), flavonoids (0.19–3.52 mg/g) and polysaccharides (58.52–547.86 mg/g) were found in the extracts. Overall, extracts from cap were more effective for the antioxidant properties assayed.