A sheet forming apparatus includes a supply port for supplying a slurry, a discharge port for discharging a green sheet, a first slurry spreading chamber, a second slurry spreading chamber, and a third slurry spreading chamber that are disposed between the supply port and the discharge port, and joining holes through which the first, second, and third slurry spreading chambers are joined to each other. At least two of the joining holes are disposed one on each side of the supply port along a transverse direction of the green sheet.