To provide a method for separating methylacetylene and 3C hydrocarbons excluding methylacetylene.

Methylacetylene and 3C hydrocarbons excluding methylacetylene are separated based on differences in the retention capability for methylacetylene and each 3C hydrocarbon excluding methylacetylene, under the same pressure and temperature conditions, of a coordinated polymer having a pillared layer structure containing a ligand represented by formula (1) and a metal ion. In the formula, X¹, X², X³, X⁴, X⁵ and X⁶ are each independently a hydrogen atom, a halogen atom or a methyl group.