Disclosed is a metal compound represented by the following formula (0): in the formula (0), A represents a thietane ring, or a monovalent group containing a thiol group; B represents a divalent group containing a heteroatom; R2 represents a divalent organic group; n represents the valence of M; p represents an integer of 1 ton; M represents a lanthanoid atom or a barium (Ba) atom when A is a thietane ring, and represents a lanthanoid atom when A is a monovalent group containing a thiol group; or more than Y represents a monovalent inorganic or organic group; when n−p is not less than 2, a plurality of Y's each independently represent a monovalent inorganic or organic group; and when n−p is not less than 2, the plurality of Y's may be bonded with each other to form a ring containing M.