When a bottle 4 made of resin is irradiated with an electron beam while it is being held by a gripper 2, an area of the bottle 4 which is shielded from the electron beam by the gripper 2 is minimized. The gripper has a pair of supports 22A, 22B positioned on opposite sides of the bottle made of resin, and abutments 24A, 24B disposed respectively on the supports 22A, 22B for holding the bottle 4 made of resin, each of the abutments 24A, 24B comprising two thin plates 26A, 28A, 26B, 28B which are vertically spaced from each other. The abutments 24A, 24B hold the bottle 4 by gripping a neck 4a of the bottle 4 on its opposite sides. While holding the bottle 4, the supports 22A, 22B are held out of contact with an outer surface of the bottle 4, allowing the electron beam to travel around the neck 4a to sterilize the entire surface of the bottle 4.
