Photoconductivity mediated by erbium ions in chalcogenide glasses Ga-Ge-S has been found. The conductivity of glasses undoped and doped with erbium has been studied under irradiation by laser light at λ = 813 nm. In both cases the optical band-gap energy exceeds by several times the laser photon energy. It has been observed that the exposure to sub-band-gap light does not change the conductivity of the undoped glass, whereas it leads to a significant increase in the conductivity of the glass doped with erbium. We propose a two-photon mechanism of the photoconductivity in this glass, where erbium accumulates laser energy and then transfers it nonradiatively to the glass matrix (energy backtransfer).