Adhesive agent composition, adhesive sheet, and electronic device

An adhesive sheet comprising a cured adhesive layer and a release sheet that is provided on one side or each side of the cured adhesive layer,

• a water vapor transmission rate calculated by an expression “A×B/60” is 30 g/(m2·day) or less, wherein A is a thickness of the cured adhesive layer [μm] and B is a water vapor transmission rate of the cured adhesive layer at a temperature of 40° C. and a relative humidity of 90% [g/(m2·day)], and
• the cured adhesive layer being formed by curing an adhesive composition comprising a diene-based rubber (A) that includes a radiation-curable functional group and a rubber-based polymer (B) that does not include a radiation-curable functional group, wherein,
• the diene-based rubber (A) is a polyisoprene rubber that includes a (meth)acryloyl group,
• the diene-based rubber (A) has a number average molecular weight (Mn) of 10,000 to 60,000,
• the rubber-based polymer (B) is an isobutylene homopolymer, a copolymer of isobutylene and n-butene, a copolymer of isobutylene and butadiene, or a copolymer of isobutylene and isoprene,
• the rubber-based polymer (B) has a number average molecular weight (Mn) of 100,000 to 2,000,000, and
• the amount of the diene-based rubber (A) is 5 to 20 parts by mass based on 100 parts by mass of the rubber-based polymer (B);
• wherein the diene-based rubber (A) comprises a polymer that comprises a repeating unit represented by a formula (I) and a repeating unit represented by a formula (II) in its molecule,
• wherein R1 and R2 are independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, X is a group represented by a formula (III),
• R3 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, m is an integer from 1 to 5, and “*” is a bonding position.