To provide a gap closing member capable of easily closing a gap formed between a frame member provided on the edge of an opening in a wall and an interior bed material provided on the surface of the bed and provide a method for constructing a surface finish sheet using the gap closing member.

This gap closing member 50 for dosing a gap 70 between a frame member 30 provided on the edge of an opening in a wall 200 and an interior bed material 40 provided on the surface of the wall 200 comprises an insertion part 51 for insertion into the gap 70 and an abutting plate 52 formed at the rear end of the insertion part 51 and fixed to the surface of the interior bed material 40. The insertion part 51 is so formed that when inserted into the gap 70 it is pressed into contact with an interior wall surface forming the gap 70. The abutting plate 52 is so formed that when the insertion part 51 is inserted into the gap 70, the abutting plate 52 closes the aperture 71 of the gap 70.