Glucosamine salts are effective for the inhibition of neutrophil functions, and hence, are useful for the prevention and/or treatment of diseases, caused as a result of an excessive extracellular release of active oxygen and antibiotic proteins by neutrophils, such as respiratory disease syndrome and adult respiratory disease syndrome. Use of glucosamine salts can, therefore, provide neutrophil function inhibitors, preventives and/or remedies for diseases caused as a result of an excessive extracellular release of active oxygen and antibiotic proteins by neutrophils, and also methods for the prevention and/or treatment of such diseases.