A reinforcing material-having functional sheet which comprises a sheet-like functional material comprising a functional 
powder and a binder resin and, laminated thereon, a reinforcing sheet comprising a 
woven fabric or a non-
woven fabric, which are bonded, wherein the basis weight of the reinforcing sheet, the 
fiber diameter of the 
fiber constituting the reinforcing sheet and the functional sheet thickness are in specific ranges. A sheet-like 
electrode for electric double layer capacitors which 
electrode comprises a sheet-like 
electrode of carbon 
fine powder and a 
fluorine-containing 
polymer resin and, laminated thereon, the reinforcing sheet, and an 
electric double layer capacitor having this electrode. The functional sheet has strength and no 
elimination of the functional material 
powder, and also efficiently exhibits high functional properties. The sheet electrode can efficiently prepare electric double layer capacitors having strength, remarkably low 
internal resistance, slight lowering of charging and discharging capabilities, excellent durability and long lifetime.