An image processing apparatus includes an image forming unit, power supplier, power controller, memory, signal transmission unit and transmission timer. The image forming unit forms an image based on image data from a plurality of host devices. The power supplier supplies power to a power system including the image forming unit. The power controller controls the power from the power supplier to the power system. The memory stores a usage amount of each host device. The signal transmission unit transmits a response request to a host device having at least a predetermined usage amount. The transmission timer counts a first time period from a transmission of the response request. The power controller halts the power from the power supplier to the power system when determining, based on the first time period, that a reply to the response request is not transmitted from the specific host device for a predetermined period.