Abstract: A propylene/ethylene-&agr;-olefin block copolymer obtained by block-copolymerizing a polypropylene component with an ethylene-&agr;-olefin random copolymer component, which satisfies conditions of the following terms (I) to (III): (I) the content of the polypropylene component having an intrinsic viscosity ([&eegr;]) measured in tetralin at 135° C. of from 0.5 to 5.0 dl/g is from 5 to 95% by weight; (II) the content of the &agr;-olefin in the random copolymer component is from 5 to 40 mol %, and the content of the ethylene-&agr;-olefin random copolymer component whose &rgr; value represented by the following equation: &rgr;=2[E]·[A]/[EA] (wherein [E] represents a molar fraction of ethylene, [A] represents a molar fraction of the &agr;-olefin and [EA] represents a molar fraction of a diad chain of ethylene and the &agr;-olefin) is within the range from 0.5 to 1.

Abstract: A propylene/ethylene-.alpha.-olefin block copolymer obtained by block-copolymerizing a polypropylene component with an ethylene-.alpha.-olefin random copolymer component, which satisfies conditions of the following terms (I) to (III):(I) the content of the polypropylene component having an intrinsic viscosity ([.eta.]) measured in tetralin at 135.degree. C. of from 0.5 to 5.0 dl/g is from 5 to 95% by weight;(II) the content of the .alpha.-olefin in the random copolymer component is from 5 to 40 mol %, and the content of the ethylene-.alpha.-olefin random copolymer component whose .rho. value represented by the following equation:.rho.=2[E].multidot.[A]/[EA](wherein [E] represents a molar fraction of ethylene, [A] represents a molar fraction of the .alpha.-olefin and [EA] represents a molar fraction of a diad chain of ethylene and the .alpha.-olefin) is within the range from 0.5 to 1.5 is from 5 to 95% by weight; and(III) the intrinsic viscosity ([.eta.]) of the propylene/ethylene-.alpha.