Signal transduction, elicited by Wnt-family of secreted proteins, can be classified intoβ-catenin-dependent canonical Wnt signaling and -independent non-canonical Wnt signaling. Non-canonical Wnt signaling contains planar cell polarity (PCP) pathway and Ca (+ +) pathway, which play central roles in developmental morphogenesis, by regulating cellular functions, including cell polarity and cell migration. In this article, we will overview the molecular basis of non-canonical Wnt signaling, with a particular emphasis on the roles of non-canonical Wnt signaling mediated by Wnt5a and its cognate receptors, Ror-family of receptor tyrosine kinases (Ror1, Ror2) , and will introduce up-to-date information on non-canonical Wnt signaling obtained from recent studies about pathological conditions, including cancer progression and chronic inflammation.