1. A color image forming apparatus, comprising: an image forming unit composed of a plurality of groups which have image carriers and image forming devices, wherein the image forming device provided around the image carrier forms a toner image on the image carrier; an intermediate transfer member which is surrounded by the plurality of groups; a primary transfer unit for transferring the toner image on the image carrier onto the intermediate transfer member to form an superimposed toner image; a secondary transfer unit which is provided at the downstream of the intermediate transfer member from the primary transfer unit, and transfers the superimposed toner image onto a transfer material; an electricity removal unit which has a discharge electrode and a grid electrode, and is provided between the primary transfer unit and the secondary transfer unit; a discharge electrode power source for applying a DC voltage with reverse polarity to the toner image on the intermediate transfer member to the discharge electrode; a grid electrode power source for applying a DC voltage with the same polarity as the toner image on the intermediate transfer member to the grid electrode; a counter electrode which is provided facing the electricity removal unit; a current detecting unit for detecting an electricity removal current flowing through the counter electrode, and a control unit for controlling an output of the electricity removal unit in accordance with a value of the electricity removal current detected by the current detecting unit.