TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The acrylic pressure sensitive adhesive composition (C1) comprises (parts by weight): the tetrafunctional epoxy compound (B) (0.1-3.0), with respect to 100 parts by weight of the carboxyl group-containing acrylic polymer (A). The acrylic polymer (A) has been prepared by copolymerizing butyl acrylate (65-75 wt.%), ethyl acrylate (15-25 wt.%), and the carboxyl group-containing compound (10-15 wt.%). The carboxyl group-containing compound is acrylic acid. Preferred Components: The double-coated adhesive sheet has an entire thickness of not less than 150 mu m. In the double-coated adhesive sheet, a ratio (T2/T1) of a total thickness (T2) of the polyester film layer and the polyimide film layer, to a total thickness (T1) of the first pressure sensitive adhesive layer, the second pressure sensitive adhesive layer and the third pressure sensitive adhesive layer, is 0.3-1.5; thickness of the first pressure sensitive adhesive layer is 10-40%, with respect to the entire thickness of the double-coated adhesive sheet; and thickness of the third pressure sensitive adhesive layer is 10-40%, with respect to the entire thickness of the double-coated adhesive sheet. The adhesive strength at an early stage of the first pressure sensitive adhesive layer is 5 to 20 N/inch. The adhesive strength of the first pressure sensitive adhesive layer is 10-30 N/inch after the double-coated adhesive sheet is allowed to stand for 1000 hours under the conditions of 85 degrees C and relative humidity (RH) of 85%. EXAMPLE - In ethyl acetate and toluene, butyl acrylate (70 wt.%), ethyl acrylate (20 wt.%) and acrylic acid (10 wt.%) were copolymerized to obtain an acrylic polymer solution having a weight-average molecular weight of 650 thousands and a glass transition temperature (theoretical value) of about -30 degrees C. With respect to a solid content of 100 parts by weight of the acrylic polymer solution, TETRAD-X (RTM: N,N,N',N'-tetraglycidyl-m-xylylenediamine) (0.8 part by weight) as a tetrafunctional epoxy compound was incorporated to obtain an acrylic pressure sensitive adhesive composition.