A transfer device transfers an image formed on each of image-carrier rotating members onto a transfer belt by applying a bias voltage to the image-carrier rotating members. A rotation axis of one of image-carrier rotating member located the most upstream is positioned closer to the transfer belt than those of the other image-carrier rotating members. Each of the bias-applying rotating members is displaced downstream of the corresponding image-carrier rotating member, and a line on which a rotation axis of the bias-applying rotating member and that of the corresponding image-carrier rotating member fall is orthogonal to a moving direction of the transfer belt.