This invention concerns a (meth)acrylic acid type polymer, wherein the value S representing the quantity of an sulfur element introduced which is defined by the formula, S=(quantity of S contained in polymer)/(total quantity of S)100, is not less than 35. This (meth)acrylic acid type polymer is a water-soluble polymer of a low molecular weight which has only a small impurity content, entails no precipitation of an impurity during the preservation at a low temperature, and excels in dispersibility, chelating ability, and an anti-gelling property.