Image forming device having a mechanism for driving a fixing roller

An image forming device, configured to form an image on a sheet in an electrophotographic method, includes a fixing roller thermally fixing a developer image on the sheet, a driving unit generating a driving force, a first rotating body configured to be driven by the driving force and rotate the fixing roller, a clutch mechanism provided on a power transmission route to transmit the driving force from the driving unit to the first rotating body, the clutch mechanism switching between a state to transmit the driving force to the first rotating body and a state to block transmission of the driving force to the first rotating body, a second rotating body provided at a downstream side relative to the clutch mechanism on the power transmission route so as to rotate in conjunction with the first rotating body, a detecting unit detecting whether the second rotating body is rotating.