An accumulating unit that discharges fibers by rotating a drum unit in which a plurality of openings are formed, a second web forming unit that forms a second web by operating a mesh belt, a sheet forming unit that forms a sheet from the second web, and a control unit that performs a start control for operating the accumulating unit and the second web forming unit from the stop state are included. In a case where the start control is performed from a state where the fibers are present in the drum unit, the control unit adjusts a thickness of the second web by controlling at least one of a timing at which rotation of the drum unit is initiated, a rotational speed of the drum unit, a timing at which movement of the mesh belt is initiated, and a movement speed of the mesh belt.