To form a very thin masking film manufactured from a high density polyethylene film with inorganic filler highly filled therein, and a tubular film for manufacturing the film.

A tubular film is manufactured such that a resin composite consisting of 100 pts. high density polyethylene and 7-50 pts. and inorganic filler (calcium carbonate) having an average particle size 1.0-1.7μm is extruded by an air cooling inflation method under specific conditions to form a tubular film having a thickness of 8-11μm, and a corona discharge treatment is effected on the inner surface and/or outer surface thereof under a condition of a wet tensile of 40 dyne/cm or more. The tubular film is used for manufacturing a masking film for coating with paint and an automobile repairing masking film.