This paper reports a polymer-based flexible Schottky diode made on a flexible cellulose substrate with poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate)-pentacene (PEDOT: PSS). Pentacene was dissolved into the N-methylpyrrolidone (NMP) solvent and mixed with PEDOT: PSS. Three-layered Schottky diodes consisting of Al, PEDOT: PSS or pentacene-PEDOT: PSS, and Au were fabricated. The current density of Au/PEDOT:PSS/Al Schottky diode (4.8 mu A/cm(2) at 2.5 V/mu m) was drastically improved to 440 mu A/cm(2) at 1.9 V/mu m when the pentacene-PEDOT: PSS was used. This enhancement of current density of Schottky diode is promising for flexible electronic devices.