It is intended to provide: an analytical method whereby the structure of a sulfated polysaccharide or a sulfated oligosaccharide can be highly sensitively analyzed； a pharmaceutical composition and a drug containing a sulfated polysaccharide or a sulfated oligosaccharide having an excellent biological activity； a method of producing a pharmaceutical composition and a drug containing a sulfated polysaccharide or a sulfated oligosaccharide； and a method of treating, diagnosing, symptom-relieving and preventing a disease. A sulfated polysaccharide or a sulfated oligosaccharide is enzymatically digested and the obtained product containing a monosaccharide, a disaccharide or a trisaccharide is analyzed by mass spectrometry. Thus, the structure of the sulfated polysaccharide or the sulfated oligosaccharide is analyzed and its qualities such as a biological activity are evaluated, which makes it possible to produce an excellent pharmaceutical composition or drug. The above-described pharmaceutical composition and drug have excellent biological activities, that have been found hereby, relating to the tumor metastasis inhibitory activity, dengue virus-infection inhibitory activity, growth factor-binding activity and so on of chondroitin sulfate.
