A powder supplying device includes: a storage section including a storage container that includes an interior space in which a powder is stored and a discharge port through which the powder is discharged from the interior space to the exterior; a roller an outer peripheral surface of which is rough and which is provided across the interior space and the exterior and configured to rotate in the discharge port; and a powder-discharging-amount adjusting section that includes a pressing member which is formed of an elastic porous body and which is pressed against the outer peripheral surface of the roller.