An apparatus for transferring toner images which is capable of executing optimum discharging control even where the environment, the material of the paper, and the kind of paper may be changed.First, the load current is detected when the transferring roller 11 is pressed to a transferring drum 6. The detected load current is converted to a characteristics detecting signal S6 at a signal converting section 109. An environment is selected on the basis of the characteristics detecting signal S6. Next, the load current flowing to the transferring roller 11 is detected when an AC discharger 14 is stopped. The detected load current is converted to characteristics detecting signal S6 at the signal converting section 109. A voltage control signal is selected based on the converted characteristics detecting signal S6, the environmental information, and the paper kind. A power source for discharging 22 is controlled by the selected voltage control signal so that the transferring becomes optimum.Accordingly, even if the kind of paper and environment is changed, optimum transferring and high transferring efficiency can be maintained.