To provide an mounting structure for a flexible film harness which can simplify the mounting work by lessening the number of parts.

The flexible film harness 1 is equipped with a plurality of insertion holes 10 consisting of H-type slits, when viewed in the thickness direction of the harness 1, piercing itself in the thickness direction at specified positions of the band-shaped harness body 2. A plurality of columnar mounting projections 11 to be inserted into the insertion holes 10 are made at the positions corresponding to the insertion holes 10 of a trim 9 serving as an attachment member. When the insertion hole 10 is inserted in the mounting projection 11, an elastic mobile piece 15 flexes in the direction of insertion, and its tip abuts on the mounting projection 11 and catches on it, so the flexible film harness 1 is fixed and attached in a state that it is pushed against the trim 9.