On the quality control of commercial Zingiberis Rhizoma and its processed product, quantitative determination of 6-gingerol using HPLC method has been conducted. Quantitative analysis off-gingerol in Zingiberis Rhizoma showed average 0.359% in 14 samples collected throughout the regions of Korea. The contents of 6-gingerol in Zingiberis Rhizome were decreased during the processing procedure (0.306%).