The present invention provides a method for sterilizing a blood purifier, which method is effective to decrease the amounts of extracts from the blood purifier attributed to the deterioration of the selectively permeable separation membranes with time during and after exposure to a radioactive ray or an electron ray, and which method is highly reliable in safety when employed for hemocatharsis therapy. The present invention also provides a blood purifier package.The present invention relates to a method for sterilizing a blood purifier which comprises substantially dried selectively permeable separation membranes as a main component, by way of the exposure of the same blood purifier to a radioactive ray and/or an electron ray, and this method is characterized in that the blood purifier is sealed in a packaging bag, together with an oxygen scavenger and a humectant or together with an oxygen scavenger capable of releasing a moisture, and is then sterilized in such a sealed state by the above exposure.