A sheet-form electrode for a secondary battery includes a current collector; an electrode active material layer formed on one surface of the current collector; a porous organic-inorganic layer formed on the electrode active material layer and including inorganic particles and a polymer binder; and a first porous supporting layer formed on the porous organic-inorganic layer. The sheet-form electrode for a secondary battery has supporting layers on at least one surface thereof to exhibit surprisingly improved flexibility and prevent the release of the electrode active material layer from a current collector even if intense external forces are applied to the electrode, thereby preventing the decrease of battery capacity and improving the cycle life characteristic of the battery.