A cleaning method for a sterilization line, the sterilization line including a conduit (3, 11) through which a product liquid is transferred, the conduit (3, 11) being provided with one or more stages of heating parts (8, 9a, 9b, 7a, 7b) that sterilize the product liquid and one or more stages of cooling parts (10a, 10b, 12, 13) that cool the product liquid from the heating parts (8, 9a, 9b, 7a, 7b) in a stepwise manner, the sterilization line including a plurality of parallel intermediate piping systems in a section thereof between a stage of a heating part (9a, 9b, 7a, 7b) that lies in a temperature range in which the product liquid can be burned and a stage of a cooling part (10a, 10b) that lies in a temperature range in which the product liquid can be burned, the section including at least the stage of a heating part (9a, 9b, 7a, 7b) that lies in a temperature range in which the product liquid can be burned, and CIP of the plurality of parallel intermediate piping systems being performed by switching between the intermediate piping systems, characterised in that switching between a flow path of the product liquid and a flow path of a cleaning solution used for the CIP upstream of the plurality of intermediate piping systems and switching between the flow path of the product liquid and the flow path of the cleaning solution used for the CIP downstream of the plurality of intermediate piping systems are achieved by a swing bend, and wherein a swing bend panel and U-shaped pipes coupled to piping ends in the swing bend panel are provided in a chamber shielded from outside air, an interior of the chamber is sterilized before the switching between flow paths, and the switching between flow paths is performed while maintaining an aseptic condition in the sterilized chamber by supplying an aseptic air into the chamber. the sterilization line including a conduit (3, 11) through which a product liquid is transferred, the conduit (3, 11) being provided with one or more stages of heating parts (8, 9a, 9b, 7a, 7b) that sterilize the product liquid and one or more stages of cooling parts (10a, 10b, 12, 13) that cool the product liquid from the heating parts (8, 9a, 9b, 7a, 7b) in a stepwise manner, the sterilization line including a plurality of parallel intermediate piping systems in a section thereof between a stage of a heating part (9a, 9b, 7a, 7b) that lies in a temperature range in which the product liquid can be burned and a stage of a cooling part (10a, 10b) that lies in a temperature range in which the product liquid can be burned, the section including at least the stage of a heating part (9a, 9b, 7a, 7b) that lies in a temperature range in which the product liquid can be burned, and CIP of the plurality of parallel intermediate piping systems being performed by switching between the intermediate piping systems, characterised in that switching between a flow path of the product liquid and a flow path of a cleaning solution used for the CIP upstream of the plurality of intermediate piping systems and switching between the flow path of the product liquid and the flow path of the cleaning solution used for the CIP downstream of the plurality of intermediate piping systems are achieved by a swing bend, and wherein a swing bend panel and U-shaped pipes coupled to piping ends in the swing bend panel are provided in a chamber shielded from outside air, an interior of the chamber is sterilized before the switching between flow paths, and the switching between flow paths is performed while maintaining an aseptic condition in the sterilized chamber by supplying an aseptic air into the chamber.