In an image forming apparatus, an electric charging member, spaced apart from an image bearer across an electric charge gap, electrically charges the image bearer uniformly across the electric charge gap. A voltage applying device applies a voltage to the electric charging member. A cleaner collects residual toner remaining on the image bearer therefrom after a transfer device transfers a toner image onto a recording medium. An electric charge gap maintaining device forms and keeps constant the electric charge gap between the electric charging member and the image bearer. A calculating device calculates a value of discharge current to be generated by the electric charging member. A processor controls the voltage applying device to vary a voltage applied to the electric charging device to render the value of discharge current calculated by the calculating device substantially constant.