To provide a polyethylene-type thermally shrinkable film for pack-in boxes, whereby it becomes possible to reduce the amount of an electric power consumed in a shrinkage tunnel without damaging a product by breakage or looseness of the film during the packaging or transportation of the product and without unduly exposing the product to high temperatures during the shrink packaging of the product due to the low-temperature shrinkability of the film, and it also becomes possible to reduce the volume of waste and the like due to the thinness of the film. Provided is a polyethylene-type thermally shrinkable multi-layer film for packaging pack-in boxes, which is a polyethylene-type multi-layer film, and is produced by biaxially stretching both in the MD and the TD and then further stretching only in the MD. Desirably, the film is a polyethylene-type thermally shrinkable multi-layer film for packaging pack-in boxes, which has an entire thickness of 25 mu m or less.