In an image transfer device for an image forming equipment, a bias for image transfer is applied from a power source to an endless transfer belt via a bias roller. A current from the transfer belt is released to ground via a ground electrode. Transfer control means variably controls a current I₁ output from the power source such that the difference between the current I₁ and a current I₂ flowing from the power source to the ground electrode via the transfer belt, i.e., I out = I₁ - 1₂ remains at a preselected target current. Setting means sets the target current on the basis of a set condition or conditions.