Elephant Yam (Amorphophallus oncophyllus), a root crop riches in glucomannan, are found in Thailand. Developing and producing of glucomannan flour in industrial scale is promising. The elephant yams which planted in Tak and Lampang provinces were extracted to be flour by two methods, dry method and wet method. The dry method was employed through sun dry and oven dry with 73% to 74% of glucomannan content in the product obtained. While the wet method using 95% ethanol as pulverizing medium resulted in higher content of glucomannan in the product up to 76% to 79%. For some physical properties of flour as viscosity and gel strength, the wet method produced flour in higher viscosity and gel strength. The viscosity and gel strength values were 15,000 cps. and 3 cm. for the flour of dry method and with 20,000 cps. and 2.7 cm. for the flour of wet method, respectively. The proximate analysis of protein, fat, crude fiber, ash and carbohydrate in the flour obtained from both processes were nearly the same with values of 3.0%, 1.0%, 3.0%, 2.0% and more than 80%, respectively. Testing of natural products of tuber and flour by chromatographic technique, it showed that all natural products that remained in tuber can be removed by wet method, while there was trace natural products in flour from dry method. The particles of flour appeared in ellipse shaped with a rough surface and ununiform sized under electron microscope. Glucose and mannose were the only monosaccharides in the product detected by HPLC. Using 3% flour and adjusted pH to 11.5 with Ca(OH)(,2) gave the highest gel strength product.