The electrical conductivity measurements of single-crystal fayalite are performed under shock wave compression in the pressure range 19.5--56 GPa. The electrical conductivity under shock compression increases by a factor of more than 1010 from 0 to 40 GPa. Over the range 19.5--42 GPa the specific conductivity &sgr; can be closely described by log10 &sgr; (S/m) =-4.65+0.15P (GPa). The conductivity versus pressure relation at room temperature is calculated by suing measured values of the activation energy to correct the high-temperature shock data to room temperature. After the effect of temperature is removed, the increase in conductivity with pressure approximatley agrees with that measured under static pressure using a diamond anvil cell by Mao and Bell. Above pressures of ~42 GPa the conductivity remains at a relatively high level of ~100 S/m from 40 to 55 GPa.