A sheet manufacturing apparatus can process various materials and manufacture a variety of sheets by changing conditions for making the sheets. A sheet manufacturing apparatus 100 according to the invention has a supply unit 10 that supplies feedstock; a defibrating unit 20 that defibrates the feedstock; a classifier 30 that classifies defibrated material that past the defibrating unit 20; a mixing unit 50 that mixes an additive containing resin with the classified material that past the classifier 30; a sieve unit 60 that passes the mixture that past the mixing unit 50 through many openings; a deposition unit 70 that deposits precipitate that past many openings in the sieve unit 60; a forming unit 80 that applies pressure and heat to the web deposited on the deposition unit 70, forming a sheet; and a control unit 90 that changes a condition of at least one of the classifier 30, mixing unit 50, sieve unit 60, deposition unit 70, and forming unit 80.