Provided is a sterilization processing line resulting from an upstream tank (16) and a downstream tank (17) that each retain a product liquid being connected by a duct (18) that transfers the product liquid, a high-temperature heating unit (21) that sterilizes the product liquid being provided to the intermediate section of the duct, one or a plurality of stages of heating units (22, 23) that heat the product liquid in stages being provided to the duct reaching from the upstream tank to the high-temperature heating unit, and one or a plurality of stages of cooling units (24, 25, 26) that cool the product liquid in stages being provided to the duct reaching from the high-temperature processing unit to the downstream tank. A plurality of parallel intermediate duct systems (P, Q) are provided at the interval from the heating unit (23) at the stage that is in a temperature range at which burning to the product liquid can occur to the cooling unit (24) at the stage that similarly is in the temperature range at which burning to the product liquid can occur, and the sterilization processing and the CIP and positive pressure holding processing of the product liquid transferred from the upstream tank to the downstream tank are performed switching between the parallel plurality of intermediate duct systems.
