LED sealing sheet suitable for manufacturing sub-millimeter LED/micro LED display devices that are resistant to ion migration in metal wiring or side electrodes even in a use environment

An object of the present invention is to provide a sealing sheet (LED sealing sheet) which is suitable for manufacturing sub-millimeter LED/micro LED display devices that are resistant to ion migration in metal wiring or side electrodes even in a use environment and is excellent in durability. The LED sealing sheet (10A) of the present invention has a laminated structure including a substrate (1) and an adhesive layer (2). The substrate (1) has a first surface (1a) and a second surface (1b). The adhesive layer (2) is laminated on the first surface (1a) of the substrate (1). The sealing material layer (2) contains an acrylic adhesive containing an acrylic polymer. The ratio of the hydroxyl group-containing monomer in all monomer components (100% by weight) constituting the acrylic polymer is 10% by weight or less. The content of carboxylic acid-based impurities in the sealing material layer (2) is 0.5 ppm or less.