A double-sided adhesive sheet has a laminate structure including a first adhesive layer containing an electrolyte, a second adhesive layer, and a conduction substrate. A double-sided adhesive sheet joined body includes, for example, an adhesive sheet having such a laminate structure, a first conductive adherend to which the first adhesive layer adheres, and a second adherend to which the second adhesive layer adheres. A method for joining/separating adherends includes joining first and second adherends to each other via the adhesive sheet, then applying a voltage to the first adhesive layer so as to generate a potential difference in a thickness direction of the first adhesive layer, and separating the first and second adherends from each other.