This study examined the quality characteristics and antioxidant activities of cookies added Pleurotus eryngii powder. There were no significant differences in bulk density or water content between the doughs. Spread factors and leavening rates of cookies decreased with increasing Pleurotus eryngii powder content. However, the loss rates of cookies showed no significant differences. L values decreased with increasing Pleurotus eryngii powder content while a values were gradually increased. b values showed no significant differences among the samples. Hardness, total phenol compound content, ferric reducing antioxidant power (FRAP) and DPPH radical scavenging activity of cookies were significantly increased with increasing Pleurotus eryngii powder content. In a descriptive test, the color, flavor, palatability, hardness and graininess were all increased with increasing Pleurotus eryngii powder content. In a preference test, color and flavor were the highest in the 10% group without significant differences. Texture was preferred in the control-20% groups without significant differences. However, taste and overall acceptability were the highest in the 10% group.