The present invention provides an immunogenic composition comprising a Streptococcus pneumoniae polysaccharide-protein conjugate, comprising a capsular polysaccharide derived from one or more selected from the group consisting of serotypes 1, 2, 3, 4, 5, 6A, 6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19A, 19F, 20, 22F, 23F, and 33F, derived from Streptococcus pneumoniae; and one or 2 or more of carrier proteins conjugated to the respective capsular polysaccharide, and method of preparation thereof. Through one example of the present invention, an immunogenic composition for preventing or treating pneumococcal infection can be provided.