A fluidized-bed furnace system having a fluidized bed furnace with a fluidized bed formed therein by a fluidized medium and an incombustible withdrawing system for withdrawing an incombustible from the fluidized-bed furnace, said incombustible withdrawing system comprising: a mixture delivery path to deliver a mixture of the fluidized medium and the incombustible from a bottom of the fluidized-bed furnace; a fluidized-bed separating chamber disposed downstream of said mixture delivery path to fluidize the mixture by a fluidizing gas and to separate the mixture into a first separated mixture having a high concentration of the fluidized medium and a second separated mixture having a high concentration of the incombustible; a return passage (391, 394) to return the first separated mixture to the fluidized-bed furnace; and an incombustible discharge passage to discharge the second separated mixture to an exterior of the fluidized-bed furnace, said incombustible discharge passage being disposed downstream of said fluidized-bed separating chamber, characterized in that: said incombustible discharge passage delivers the second separated mixture vertically upward and discharges the second separated mixture from a position located higher than a surface of the fluidized bed to the exterior of the fluidized-bed furnace; and a fluidized medium delivering device is provided to deliver the second separated mixture in said incombustible discharge passage with at least an angle of repose of the fluidized medium with respect to a horizontal plane. a mixture delivery path to deliver a mixture of the fluidized medium and the incombustible from a bottom of the fluidized-bed furnace; a fluidized-bed separating chamber disposed downstream of said mixture delivery path to fluidize the mixture by a fluidizing gas and to separate the mixture into a first separated mixture having a high concentration of the fluidized medium and a second separated mixture having a high concentration of the incombustible; a return passage (391, 394) to return the first separated mixture to the fluidized-bed furnace; and an incombustible discharge passage to discharge the second separated mixture to an exterior of the fluidized-bed furnace, said incombustible discharge passage being disposed downstream of said fluidized-bed separating chamber, characterized in that: said incombustible discharge passage delivers the second separated mixture vertically upward and discharges the second separated mixture from a position located higher than a surface of the fluidized bed to the exterior of the fluidized-bed furnace; and a fluidized medium delivering device is provided to deliver the second separated mixture in said incombustible discharge passage with at least an angle of repose of the fluidized medium with respect to a horizontal plane. said incombustible discharge passage delivers the second separated mixture vertically upward and discharges the second separated mixture from a position located higher than a surface of the fluidized bed to the exterior of the fluidized-bed furnace; and a fluidized medium delivering device is provided to deliver the second separated mixture in said incombustible discharge passage with at least an angle of repose of the fluidized medium with respect to a horizontal plane.