An adhesive for filling in gaps between stones, the adhesive including at least 100 weight parts of an unsaturated polyester resin suitable for air-drying, between 1 and 5 weight parts of hydrogenated castor oil, between 0 and 60 weight parts of micron silica, and between 1 and 15 weight parts of an anti-shrinking agent. The adhesive overcomes the disadvantages of conventional marble glue, such as, poor air-drying property, poor shrinkage resistance, and poor permeability. The adhesive of the invention has good permeability, strong shrinkage resistance, and high brightness after being polished, and is not sticky after curing. The invention solves the difficulty of gap-filling of stone by providing a new category of marble glue.