An image forming device and a sheet conveyance method are provided. An image forming device includes a feeder, a first conveyor, a second conveyor, and a conveyance controller. The feeder aligns a sheet and feeds the sheet to a transfer system that transfers an image to the sheet. The first conveyor is arranged at a first position on an upstream side of the feeder in a sheet conveyance direction and conveys the sheet to the feeder. The second conveyor is arranged at a second position on an upstream side of the first conveyor in the sheet conveyance direction and conveys the sheet to the first conveyor. The conveyance controller performs high-speed control for causing a conveyance speed of the second conveyor to exceed a conveyance speed of the first conveyor when a specific sheet different from a normal sheet is fed by the feeder.