There is no problem of drying due to volatilization of water or an organic solvent, and an electrode structure including an adhesive layer exhibiting sufficient conductivity and excellent adhesiveness, a biological signal measuring device including the electrode structure, and the electrode A pressure-sensitive adhesive forming composition that is suitably used as a pressure-sensitive adhesive layer in a structure. In an electrode structure comprising a conductive pressure-sensitive adhesive layer, a support that supports the pressure-sensitive adhesive layer, and a wiring or a terminal connected to the pressure-sensitive adhesive layer, the content of water and organic solvent in the pressure-sensitive adhesive layer The volume resistivity of the pressure-sensitive adhesive layer is 1500 Ωcm or less.水や有機溶剤の揮発による乾燥の問題がなく、且つ十分な導電性と優れた粘着性とを示す粘着剤層を備える電極構造体と、当該電極構造体を備える生体信号計測装置と、当該電極構造体における粘着剤層として好適に使用される粘着剤形成用の組成物と、を提供すること。 導電性の粘着剤層と、粘着剤層を支持する支持体と、粘着剤層に接続される配線又は端子と、を備える電極構造体において、粘着剤層中の水及び有機溶剤の含有量を１０質量％以下とし、粘着剤層の体積抵抗率を、１５００Ωｃｍ以下とする。
