A large response of electric resistance to hydrostatic pressure is observed in graphite-papostor (the mixture of graphite, paraffin and polyethylene). The piezoresistance coefficient is -1700∼-2800×10-12 cm2/dyne under a hydrostatic pressure of 0∼700 kg/cm2. This coefficient is comparable with those of some organometallic compounds. The piezoresistance coefficient under uniaxial compression is positive and its characteristics are essentially different from those of the coefficient under hydrostatic pressure.