NOVELTY - An impregnated paper obtained by impregnating a thermosetting resin composition into carbon short fiber paper after the carbon short fiber is dispersed at random in two-dimensional plane is hot-pressed at predetermined temperature, the press pressure is released, and the thermosetting resin composition is hardened and carbonized in an inert gas atmosphere to obtain a porous electrode base material.    USE - Manufacture of porous electrode base material used for polymer electrolyte fuel cell.    ADVANTAGE - The method enables manufacture of porous electrode base material having high air permeability. The crack initiation in the porous electrode base material by rapid cure shrinkage or hole occlusion is suppressed.    DETAILED DESCRIPTION - An impregnated paper obtained by impregnating a thermosetting resin composition into carbon short fiber paper after the carbon short fiber is dispersed at random in two-dimensional plane is hot-pressed at predetermined temperature, the press pressure is released, and the thermosetting resin composition is hardened and carbonized in an inert gas atmosphere to obtain a porous electrode base material. The hot-press temperature is determined by attaching a probe needle with diameter of 3 mm in a heating furnace of an apparatus for thermomechanical analysis, attaching a sample stand with diameter of 9 mm under the probe needle, providing the impregnated paper sample with diameter of 3-10 mm on the sample stand, applying vibrational load of 0.01 Hz and plus minus 1.5 N to the impregnated paper sample which is heated inside the heating furnace by 2 degrees C/minute, recording displacement of the probe needle from room temperature to 250 degrees C and extracting a non-oscillatory component from the recorded displacement by moving from low temperature side to high temperature side to form graph with a portion (a) into which displacement decreases rapidly, a portion (b) into which displacement gradually reduces, a portion (c) into which displacement decreases rapidly again and a portion (d) into which displacement increases gradually, and the temperature of the portion which displacement gradually reduces is the hot press temperature.    DESCRIPTION OF DRAWING(S) - The drawing shows the schematic view of the temperature-displacement curve. (Drawing includes non-English language text)    Portions into which displacement decreases rapidly (a,c)    Portion into which displacement gradually reduces (b)    Portion into which displacement increases gradually (d)