PURPOSE: To make it possible to easily produce packing bags of several kinds of specifications continuously without stopping machines when chemical fibers are packed under compression.

CONSTITUTION: A compression packing device is such that cotton-like materials to be packed such as tows or staple fibers are compressed by means of a pair of press boards 1, 2 vertically opposed and bands are inserted into grooves formed on the press surfaces of the boards 1, 2 through binding material guides 4a, 4b inserted into the grooves to wrap the material 3 to tighten it. The depth of the grooves formed on the boards 1, 2 is made larger to allow relative vertical movement of the boards 1, 2 with respect to the inserted guides 4a, 4b, while a plurality of positioning sensors 7a-7c are parallelly provided to set compression height of said boards. Further when the height of packing bag is decreased, downward ones of the sensors 7a-7c are selected to actuate. On the contrary, when the height of the bags is increased, the sensors on the upper side are selected. As a result, various packing bags whose height and weight continuously varies can be produced.