Abstract: The present invention is an adjusting device used for adjusting and leveling a plurality of tiles on a floor or a wall during an installation, the adjusting device comprises of a clip which is placed underneath a laying surface of at least two adjacent tiles and comprises of a top portion in vertical plane, and it has an opening which receives a first wedge and has three sharp edges around the opening to grab the first wedge, a bottom plate in horizontal plane comprises of a flat base having at least two support protrusions at each side to support a tile, and a first wedge has two triangle faces and one quadrilateral face having teeth to be engaged with the opening in the clip, so the first wedge presses the tiles towards the bottom plate of the clip in such a way to level the tiles.