Microwave heating is faster than the conventional way, therefore it is interesting to apply for cocoa roasting. This research was aimed at gaining information on the effect of microwave roasting of ground cocoa nib on the antioxidative properties of crude polyphenol extract from the product.The results indicated that microwave roasting of ground cocoa nib for 5 min, adjusted at 20% of the full power (900W) gave no significant difference in inhibition of linoleic acid oxidation and scavenging of DPPH radical activity of the crude polyphenol extract compared to that of the conventional roasting at 140 oC for 40 min. But having reduction of ferric ion activity more greater and chelating ferro ion activity more lower. The crude polyphenol extract inhibited linoleic acid oxidation and scavenged DPPH free radical. The inhibition was lower than that of either BHT or a-tocoferol at concentration lower than 400 ug/ml for linoleic acid oxidation and that lower than 40 ug/ml for DPPH free radical scavenging. The crude polyphenol extract reduced ferric ion, though lower than BHT did.