It is intended to provide a dietary fiber composition containing Amorphophallus konjac as an ingredient for an easy-to-take functional food, a controlled-release drug or the like, and it is obtained by adding and mixing water in Amorphophallus konjac with an average molecular weight of 50,000 or more purified using an alcohol from a matter in which starch is separated and removed from a tuber of Amorphophallus konjac plant and an inclusion agent which suppresses a water-absorbing property of Amorphophallus konjac. Further, it can also be obtained by adding and mixing water in one or more members selected from polysaccharide thickeners consisting of Amorphophallus konjac, seed coat of Plantago ovata (psyllium), carrageenan, xanthan gum, curdlan, pectin, gum Arabic, chitin, chitosan, guar gum, gellan gum, tara gum, tamarind gum, tragacanth gum and pullulan and an inclusion agent which suppresses a water-absorbing property of the polysaccharide thickeners.