A permeation-preventive member and a multilayered container for fuel tank employing the permeation-preventive member, the permeation-preventive member is for preventing a permeation of hydrocarbon compound by fusion-bonding the member to a discontinuous part of the permeation-preventive layer in a multilayered container for fuel tank which comprises an inner polyolefin resin layer, an outer polyolefin resin layer and a permeation-preventive layer as an interlayer, wherein the permeation-preventive member comprises a metal sheet or foil and an adhesive resin layer comprising a modified polyolefin that satisfies the following requirements (a) to (e): (a) the melt flow rate as measured at a temperature of 190° C. under a load of 2.16 kg is 0.1-100 g/10 min; (b) the density is 0.910-0.965 g/cm3; (c) the initial adhesive strength to the metal sheet or foil is 0.1 kg/10 mm or higher; (d) the adhesive strength to the metal sheet or foil as measured after 2,500-hour immersion at 65° C. in a mixed solvent composed of 45 parts by volume of 2,2,4-trimethylpentane, 45 parts by volume of toluene, and 10 parts by volume of ethyl alcohol is 0.1 kg/10 mm or higher; and (e) the proportion of the adhesive strength (d) to the initial adhesive strength (c) is 50% or higher.