Adhesive agent and adhesive sheet

An adhesive sheet comprising an adhesive agent layer comprising adhesive agent comprising a crosslinked adhesive agent composition which comprises a polyester resin (i) having a structural portion derived from a polycarboxylic acid compound (a) and a structural portion derived from a polyol component (b),

• wherein not less than 60 wt. % of a total weight of the polyester resin (i) comprises a structural portion derived from at least one selected from the group consisting of a dimer acid compound, a sebacic acid compound, and a dimer diol,
• wherein the polyol component (b) comprises a glycol (b1) having an even carbon number, excluding the dimer diol,
• wherein the polyester resin (i) has a weight-average molecular weight of greater than 50,000 to 500,000 or less,
• wherein the polyester resin (i) has an ester group concentration of from 3 to 10 mmol/g, and
• wherein the adhesive agent layer has a gel fraction of 10 to 49 wt. %,
• the adhesive agent having an adhesive force (x) of not less than 1 N/25 mm as measured as a 180-degree peel strength (N/25 mm) by forming an adhesive agent layer of the adhesive agent on a substrate to provide an adhesive sheet, bonding the adhesive sheet to an adherend of a bright annealed stainless steel plate, allowing the resulting structure to stand still at 23° C. at 50% RH for 30 minutes, and peeling the adhesive sheet from the adherend at a peel rate of 300 mm/minute.