A polyolefin-based structure includes 60 to 97% by mass of a polyolefin (A), 1 to 35% by mass of an acid-modified polyolefin (B), and 2 to 35% by mass of a polyamide resin (C), in which the polyamide resin (C) is dispersed in a layered form in the polyolefin (A), and the polyamide resin (C) is a melt-kneaded product of 30 to 70% by mass of a polyamide (X) that contains a diamine unit containing 70 mol % or more of a m-xylylenediamine unit and a dicarboxylic acid unit containing an α,ω-linear aliphatic dicarboxylic acid unit and 30 to 70% by mass of an aliphatic polyamide (Y) (provided that a total of the polyamide (X) and the polyamide (Y) is taken as 100% by mass), and a difference between a melting point Tm0 of the polyamide (X) as observed by differential scanning calorimetry and a melting point Tm1 derived from the polyamide (X) in the polyamide resin (C), is 0.1 to 2.5° C.