PROBLEM TO BE SOLVED: To provide a polymer which exhibits excellent treatability and putrefaction resistance compared with the conventional polymers.SOLUTION: The acrylic acid base polymer composition comprises: (i) an acrylic acid base polymer essentially having a structural unit expressed by general formula (1), and in which weight-average molecular weight is 2,000 to 50,000； and (ii) propionic acid (salt), and in which the content of the propionic acid (salt) is 50 ppm to 0.5 mass% to the acrylic acid base polymer. In the general formula (1), M denotes alkali metals such as a hydrogen atom, a lithium atom, a sodium atom and a potassium atom, alkaline-earth metals such as calcium and magnesium, ammonia and quaternary amine salt.
