Several analytical approaches are available for investigating the antioxidant power for antioxidants, and they are based on a variety of chemical principles, such as oxygen radical absorbance capacity (ORAC), Trolox equivalent antioxidant capacity (TEAC), and ferric reducing/antioxidant power (FRAP). This paper reports a new rapid method for investigating antioxidant power on the basis of the electron-donating ability. This method is called chemiluminescence analysis of antioxidant power (CAAP). The electrons donated from antioxidants are capable of inducing chemiluminescence in the presence of lucigenin and a base. Thus, the intensity of chemiluminescence induced by antioxidants is proportional to their electron-donating ability (antioxidant power). It was found that the correlation between CAAP and FRAP was positive (r = 0.959) and statistically significant (p < 0.05). In addition to the FRAP assay, the rapid CAAP assay is convenient for investigating the antioxidant power of herbal extracts.