[PROBLEMS] To provide an efficient sterilization method for inexpensively sterilizing a medical article having a complex shape such as a body fluid treatment device of a generally-called dry or semi-dry type by so applying an electron beam that the overall absorbed dose distribution is small and to provide its application package form. [MEANS FOR SOLVING PROBLEMS] A method for sterilizing tubular body fluid treatment devices of a dry or semi-dry type contained in an electron beam-transmitting case with an electron beam. The method is characterized in that a stack structure which includes a gap layer having an average density of 0.010 to 0.180 g/cm 3 and two body fluid treatment device layers having an average density of 0.050 to 0.200 g/cm 3 and sandwiching the gap layer is contained in the electron beam-transmitting case, and the case is irradiated with the electron beam.
