To provide a sack for fluorescent tube, which rigidly supports a straight-pipe-type fluorescent tube by arc press ribs and supports on a number of points in a high density.

According to the sack, a composite paperboard 3' comprising a buffer paper 1' with the ribs and a facing paper 2' is bent into a rectangular cylinder via line-pressing folding lines for compressively deforming interior ribs 4a' of the buffer paper. Two sides of the composite paperboard 3' are set opposed to each other at one side face of the rectangular cylinder, and a paper tape 6' is stuck across the two sides, so that each rib is extended circumferentially on the inner/outer surfaces of the cylinder and is arranged axially in parallel to each other. When the straight-pipe-type fluorescent tube 7 is inserted in the rectangular cylinder, each interior rib 4a' is compressedly deformed by the arc surface of the tube 7 at four sides of the cylinder to support the tube. In the sack, the height of each rib 4a', 4b' is set to be 0.4 to 0.7 mm, and the gap between respective axially arranged ribs is set to be 1.5 to 3.0 mm.