An image forming device includes a toner pattern forming unit that forms a first toner pattern and a second toner pattern downstream of the first toner pattern along a direction of advance of the transfer belt on the transfer belt. The first toner pattern is configured to include color patches of which a color density gradually differs so that, when detected by a sensor, a fluctuation of the toner density is adjusted by a feedback data. The second toner pattern is configured to prevent a cleaning blade from being twisted by a friction of an intermediate belt due to the toner lubrication.