The challenge of chemical glycan synthesiscontinues to address the preparation of highly diverse and biologically active glycans since the synthetic glycans have been prepared as a single glycan structure. It is significant to consider and prepare methods so that all bonding patterns, which still have problems with yield and stereo-selectivity, can be freely synthesized in response to sugar residues. Each study on synthetic glycans can be extended to the synthesis of complex carbohydrates and glycan probes, which are extremely diverse and offer great potential for achieving a wide range of biological activities. Researches related to human health including vaccine development against pathogenic bacteria and discovery of novel glycan-related enzymes in intestinal bacteria are important issues to be accomplished by using unique synthetic glycans.