The present invention relates to an olefin-based polymer, which has (1) a density (d) ranging from 0.85 to 0.90 g/cc, (2) a melt index (MI, 190° C., 2.16 kg load conditions) ranging from 0.1 g/10 min to 15 g/10 min, (3) the density (d) and the melt temperature (Tm) satisfying Tm (° C.)=a×d−b of Equation 1 (2,350