Disclosed herein is a silicon adhesive composition for transporting a flexible substrate. The composition includes (A) 42 to 70 parts by weight of a polydiorganosiloxane containing an alkenyl group, (B) 55 to 28 parts by weight of a polyorganosiloxane copolymer including R13SiO1/2 units and SiO2 units, wherein R1 is a hydroxy group or a monovalent hydrocarbon group of 1 to 12 carbon atoms, (C) a polyorganosiloxane containing an SiH group, wherein the molar ratio of the SiH group of component (C) to the alkenyl group of component (A) is from 0.5 to 20, and (D) a platinum group catalytic compound, wherein the weight ratio of a metal component of the compound to the sum of components (A) and (B) is from 1 to 5000 ppm by weight.