Provided are a propylene-based polymer useful for providing a toner that is excellent in offset resistance, can be fixed by using a low-temperature heating element and hardly has stickiness even after stored for a long period of time; and a toner including said propylene-based polymer. The present invention is directed to a propylene/α-olefin copolymer (A) which includes 60 to 90 mol % of structural units derived from propylene (a) and 10 to 40 mol % of structural units derived from α-olefins having 4 or more carbon atom (b) wherein (a)+(b)=100 mol % and which satisfies: (i) a weight average molecular weight (Mw) as measured by GPC of 3,000 to 40,000; (ii) a melting point (Tm) as measured by DSC of 60 to 90° C.; and (iii) a half width of a crystalline melting point peak as measured by DSC of 1 to 20° C.