A LOW-MOLECULAR-WEIGHT POLYSULFATED HYALURONIC ACID DERIVATIVE USEFUL FOR PREVENTION AND/OR TREATMENT OF AN ALLERGIC DISEASE.AN AGENT FOR PREVENTION AND/OR TREATMENT OF AN ALLERGIC DISEASE SELECTED FROM POLLINOSIS, ALLERGIC RHINITIS, ALLERGIC CONJUNCTIVITIS, ATOPIC DERMATITIS, AND ASTHMA, REPRESENTED BY THE FOLLOWING GENERAL FORMULA (IA) OR (IB); WHEREIN N REPRESENTS A NUMBER OF 1 TO 15; R1S EACH INDEPENDENTLY REPRESENT A HYDROGEN ATOM OR AN SO3H GROUP ETC.