A present sheet manufacturing apparatus, which manufactures a sheet including defibrated material and whiteness enhancer, is provided with a defibrating unit configured to defibrate a stock material that includes fibers, a whiteness enhancer feeding unit configured to feed the whiteness enhancer to the defibrated material defibrated in the defibrating unit. A feeding amount of the whiteness enhancer is changed based on whiteness information of the stock material or the defibrated material.