To provide a method for sterilizing granular material such as grain by thoroughly irradiating the whole surface of each of the granular material with electronic beam with low energy, and further to provide an apparatus to be used in the method.

This method for sterilizing the granular material 3 is characterized in that the surface of the floating and migrating granular material 3 is irradiated with the electronic beam F with the low energy. The floating, migrating and sterilizing apparatus has a feeding device 1 for dropping and feeding the granular material 3 in an irradiation chamber 2, an ascending current- generating device 4 for sending a gas from the lower part of the irradiation chamber 2, and an electron beam-accelerating tool 9 for radiating the electron beam F with the low energy from the side surface of the irradiation chamber 2, installed in the middle position between both of the devices.