NOVELTY - Adsorption of saturated hydrocarbon involves contacting a mixture containing 3C or less saturated hydrocarbon and unsaturated hydrocarbon with a metal complex containing a metal ion and a ligand (L1) (I) which is functional group-containing saturated compound, and selectively adsorbing saturated hydrocarbon to the metal complex.    USE - Adsorption of saturated hydrocarbon e.g. propylene and propane.    ADVANTAGE - The method enables economical and selective adsorption of saturated hydrocarbon to metal complex. The saturated hydrocarbon and unsaturated hydrocarbon are separated efficiently using the small-sized hydrocarbon separation apparatus, with reduced energy consumption.    DETAILED DESCRIPTION - Adsorption of saturated hydrocarbon involves contacting a mixture containing 3C or less saturated hydrocarbon and unsaturated hydrocarbon with a metal complex containing a metal ion and a ligand (L1) of formula (I) which is functional group-containing saturated compound and a metal ion, and selectively adsorbing saturated hydrocarbon to the metal complex.    P'=saturated hydrocarbyl containing substituent other than Ra', 1st ligand is the C3-C12 saturated hydrocarbon group which may be substituted by the C1-C8 saturated hydrocarbon group and which has a cyclic structure;    Ra'=functional group having coordinating property in relation to metal ions;and    m=1-4.    INDEPENDENT CLAIMS are included for the following:    (1) separation of hydrocarbon, which involves separating the saturated hydrocarbon using adsorption method of saturated hydrocarbon; and    (2) apparatus for separating hydrocarbon, which consists of a separation unit (1) provided with the metal complex, and an introduction unit (2) which introduces the mixture to the separation unit, contacts the mixture with metal complex, adsorbs the saturated hydrocarbon to the metal complex, and separates the unsaturated hydrocarbon.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of hydrocarbon separation apparatus. (Drawing includes non-English language text)    Separation unit (1)    Introduction unit (2)    Pressure control unit (3)    Control unit (4)    Valves (V1,V2,V3,V4,V5,V6)