A bag for packaging heavy materials, exhibiting excellent strength, content packaging performance, stacking performance on the pallets, and anti-collapsing performance. The bag is made of a multi-layer laminated film which comprises an outermost layer of a polyethylene film containing an inorganic filler in an amount of from 20 to 80% by weight and an innermost layer of a polyethylene film containing an inorganic filler in an amount of from 10 to 40% by weight, the outermost layer having on the surface thereof a coefficient of static friction of not smaller than 0.5 (ASTM D 1894), a coefficient of dynamic friction of not larger than 0.5 (ASTM D 1894) and a gloss of not larger than 50% (JIS Z 8741, at a measuring angle of 60.degree.), and the content of the inorganic filler in the innermost layer being from 1/2 to 1/6 of the content of the inorganic filler in the outermost layer.