An encapsulating sheet, for encapsulating an optical semiconductor element, includes an embedding layer for embedding the optical semiconductor element, a covering layer disposed at one side in a thickness direction with respect to the embedding layer, and a barrier layer interposed between the embedding layer and the covering layer; having a thickness of 50 µm or more and 1,000 µm or less; and for suppressing a transfer of a component contained in the covering layer to the embedding layer.