The present invention provides a single-layer shape retaining material excellent in mechanical strengths, such as tensile elastic modulus and tensile strength, as well as in non-directional shape retaining properties; and a method for producing the same. The shape retaining material is a fibrous, band-like, or sheet-like stretched formed material comprising 100 parts by weight of a high-density polyethylene resin having a weight-average molecular weight of 100,000 to 500,000 and a density of 0.945 to 0.960 g/cm 3 and 3 to 50 parts by weight of an ethylene-±-olefin copolymer obtained by copolymerizing ethylene with an ±-olefin having 4 to 10 carbon atoms, the copolymer having a density of 0.935 to 0.960 g/cm 3 , the difference in density between the copolymer and the high-density polyethylene resin being ± 0.020 g/cm 3 or less, wherein the material shows, after being bent at an angle of 180 degrees in a direction orthogonal to the stretching direction, held in the bent state for 1 minute, released, and left for 5 minutes after the release, a return angle of 15 degrees or less; and shows, after being bent in a direction parallel to the stretching direction, a return angle of 25 degrees or less.