The invention provides a water-soluble dietary fiber enriching agent comprising a modified starch which contains dietary fibers in an amount not more than 5% by mass measured by Prosky's method and a low-molecular weight water-soluble dietary fiber in an amount not less than 25% by mass. The water-soluble dietary fiber enriching agent contains a low-molecular weight water-soluble dietary fiber, and does not deteriorate the mouthfeel of the food obtained using the same.