A sheet conveyor device includes a registration roller, an intermediate roller, a first sheet detection section, a first drive controller, a second drive controller, and a third drive controller. The registration roller conveys a sheet toward an image forming section for image formation. The intermediate roller conveys the sheet toward the registration roller. The first sheet detection section is used for optically detecting the sheet between the registration roller and the intermediate roller. The first drive controller drives the intermediate roller, while suspending driving of the registration roller. The second drive controller drives the registration roller when a predetermined conveyance wait period elapses from detection of a sheet by the first sheet detection section. The third drive controller drives the registration roller when a predetermined forced conveyance period elapses from a start of conveyance of the sheet loaded on a sheet loading section.