A method of reusing hydrogen in an exhaust purge gas, comprising: a silane removal step of removing silanes from an exhaust gas discharged from a step of producing polysilicon by reacting hydrogen with a trichlorosilane, prior to: a hydrogen chloride adsorption step of adsorbing the hydrogen chloride by passing the exhaust gas through an active carbon layer; a hydrogen chloride desorption step of desorbing the adsorbed hydrogen chloride by passing a hydrogen gas as the purge gas through the active carbon layer that has adsorbed and held the hydrogen chloride; a hydrogen recovery step of obtaining the hydrogen gas from which the hydrogen chloride has been removed by bringing, into contact with a hydrogen chloride-absorbing solution, the exhaust purge gas that contains hydrogen and the hydrogen chloride desorbed in said hydrogen chloride desorption step; and a hydrogen feed step of compressing the hydrogen gas recovered in said hydrogen recovery step and feeding the hydrogen gas as a hydrogen source for other steps; and wherein provision is made of: (i) a water washing step of washing with water the hydrogen gas recovered in the hydrogen recovery step prior to the hydrogen feed step; and (ii) a step of bringing the hydrogen gas washed with water in the water washing step into contact with a silane-trapping agent prior to the hydrogen feed step or during the compression in the hydrogen feed step and, thereafter, separating, from the hydrogen gas, the silane-trapping agent that accompanies the hydrogen gas, wherein the silane-trapping agent is an organic solvent or an oil. a silane removal step of removing silanes from an exhaust gas discharged from a step of producing polysilicon by reacting hydrogen with a trichlorosilane, prior to: a hydrogen chloride adsorption step of adsorbing the hydrogen chloride by passing the exhaust gas through an active carbon layer; a hydrogen chloride desorption step of desorbing the adsorbed hydrogen chloride by passing a hydrogen gas as the purge gas through the active carbon layer that has adsorbed and held the hydrogen chloride; a hydrogen recovery step of obtaining the hydrogen gas from which the hydrogen chloride has been removed by bringing, into contact with a hydrogen chloride-absorbing solution, the exhaust purge gas that contains hydrogen and the hydrogen chloride desorbed in said hydrogen chloride desorption step; and a hydrogen feed step of compressing the hydrogen gas recovered in said hydrogen recovery step and feeding the hydrogen gas as a hydrogen source for other steps; and wherein provision is made of: (i) a water washing step of washing with water the hydrogen gas recovered in the hydrogen recovery step prior to the hydrogen feed step; and (ii) a step of bringing the hydrogen gas washed with water in the water washing step into contact with a silane-trapping agent prior to the hydrogen feed step or during the compression in the hydrogen feed step and, thereafter, separating, from the hydrogen gas, the silane-trapping agent that accompanies the hydrogen gas, wherein the silane-trapping agent is an organic solvent or an oil. (i) a water washing step of washing with water the hydrogen gas recovered in the hydrogen recovery step prior to the hydrogen feed step; and (ii) a step of bringing the hydrogen gas washed with water in the water washing step into contact with a silane-trapping agent prior to the hydrogen feed step or during the compression in the hydrogen feed step and, thereafter, separating, from the hydrogen gas, the silane-trapping agent that accompanies the hydrogen gas, wherein the silane-trapping agent is an organic solvent or an oil.