An image forming device comprises; an endless-belt shaped image carrier that circulates along a predetermined locus of movement and is trained around a plurality of rollers, the plurality of rollers being structured by at least one driving roller that receives driving force from a drive source and drives, and driven rollers that do not have drive force, a dynamic friction connecting unit that, by dynamically-frictionally connecting the driving roller and at least one of the driven rollers under a predetermined dynamic friction coefficient, dynamically-frictionally drives the at least one driven roller by driving force of the driving roller.