A sheet manufacturing apparatus is provided with a screen portion in which introduced material is passed through a plurality of openings; an information acquiring unit configured to acquire at least one of inflow information related to a flow rate of the material that flows into the screen portion and outflow information related to a flow rate of the material that passes through the screen portion; and a controller configured to make a determination that a clogging of the screen portion is generated when the flow rate is reduced based on at least one of the inflow information and the outflow information.