According to one embodiment, an image forming apparatus includes an image forming portion, and a control portion. The image forming portion includes an image carrier, a charging device, and a cleaning device. The charging device includes a charging roller which contacts a surface of the image carrier. The cleaning device includes a cleaning blade, and an adjustment portion. The cleaning blade slidably contacts the surface of the image carrier. The adjustment portion adjusts a linear pressure of the cleaning blade exerted on the surface of the image carrier. The control portion executes, when a rate of increase of an outer layer resistance value of the charging roller caused by a decrease in the function of the cleaning blade is greater than or equal to a first rate, linear pressure adjustment control of controlling the adjustment portion to increase the linear pressure of the cleaning blade.