In an image-forming apparatus such as a printer, a controller judges whether or not a determination processing of fixity saturation state is performed to determine a fixing condition in which an image density of a patch is the fixity saturation state. The controller then performs the determination processing of fixity saturation state when a use condition is changed. The controller settles fixing conditions in which the image density of patch is highest as the set value when the image density of the patch is saturated. Next, the controller performs a toner adhesion amount adjustment using an intermediate transfer belt. A target value of the toner adhesion amount on the intermediate transfer belt corresponding to the target image density is set and then, an optimal developing voltage that is the set target value is set. After the toner adhesion amount adjustment, the controller performs fixity adjustment.