PROBLEM TO BE SOLVED: To quickly and easily sterilize preforms.SOLUTION: Multiple preforms (1) formed in the shape of bottomed cylinders are placed on a conveyor (4) and placed in an uneven and side-lying state. These preforms are passed through a chamber (5) for each conveyor. Inside the chamber the preforms are sprayed from both sides of the conveyor with hydrogen peroxide solution in a direction across the conveyor. The sprayed hydrogen peroxide solution is deposited on the inner and outer surfaces of the preforms (1) on the conveyor.