Since 1982, Wnt1 (Wingless int-1) was first identified in mammary carcinoma. Further, Wnt signaling pathway was discovered. Wnt signals were involved in stem cells development, regeneration, cell cycle and repair mechanism. Finally abnormality Wnt signals were stimulated variety of cancers. Especially, non-canonical signaling pathways such as Wnt/PCP and Wnt/Ca2+ pathway were involved in development process. These pathways regulated stem cells and organ development such as cell polarity, adhesion, cell shape and cell movement. Despite, aberrant expression of non-canonical pathway induced tumorigenesis in development. In clinical studies, drugs were developed against cancer cells not in cancer stem cells. Drugs will synthesis against cancer stem cells based on the activation of abnormality of Wnt signaling.