There is provided a dispersion device including: a supply section having a supply pipe for supplying a material containing fibers together with air, and a chamber that has a first swirl flow forming portion forming a first swirl flow of the air containing the material and a second swirl flow forming portion communicating with the first swirl flow forming portion and forming a second swirl flow in a direction opposite to the first swirl flow of the air containing the material and that is coupled to the supply pipe; a dispersion section that has a casing formed with a discharge port for discharging the material, stirs the material in the casing, and discharges and disperses the material from the discharge port into air; and a coupling section having a communication port through which the first swirl flow forming portion and the second swirl flow forming portion communicate with the casing.