Provided are: an alkoysilyl group-containing hydrogenated block
copolymer produced by introducing an alkoxysilyl group into a hydrogenated block
copolymer that is obtained by hydrogenating 90% or more of
unsaturated bonds of a block
copolymer that includes at least two
polymer blocks [A] and at least one
polymer block [B], the
polymer block [A] including a repeating unit derived from an aromatic vinyl compound as a main component, the polymer block [B] including a repeating unit derived from a linear
conjugated diene compound as a main component, and a ratio (wA:wB) of a weight fraction wA of the polymer block [A] in the block copolymer to a weight fraction wB of the polymer block [B] in the block copolymer being 20:80 to 60:40; a method for producing the same; a
solar cell element encapsulating material; a sheet, a laminated sheet; a multilayer sheet; and a method for encapsulating a
solar cell element. The alkoxysilyl group-containing hydrogenated block copolymer exhibits low hygroscopicity, a low
water vapor permeability, transparency, weatherability, and flexibility, maintains excellent adhesion to glass even when exposed to a high-temperature / high-
humidity environment for a long time, and can encapsulate a
solar cell element without applying a special waterproof treatment.