A separating material superior to conventional separating materials, and a separation method are provided, with which 1,3-butadiene is selectively separated and recovered from a mixed gas including 1,3-butadiene and C4 hydrocarbons other than 1,3-butadiene. A metal complex, which comprises a dicarboxylic acid compound (I) (see (I) below) represented by general formula (I), an ion of a metal such as beryllium, and a dipyridyl compound (II) represented by general formula (II), namely L-Z-L (II) (see L below), is characterized by including, as the dipyridyl compound (II), at least two different dipyridyl compounds (II). The metal complex is used as a 1,3-butadiene separating material. Formula (I) L is represented by any of the compounds below.