To provide a method for manufacturing a syringe capable of being easily and properly filled with an injection in an aseptic manner, and easily feeding the injection as a mixture of two components to an outer cylinder in an aseptic manner at the time of use.

Regarding a method for manufacturing a syringe 1 having an outer cylinder 2 preliminarily filled with an injection, filling holes 2A and 2B are formed on the prescribed plastic molded wall of the outer cylinder 2, and liquidtight filling chambers 7A and 7B are formed between a gasket 4 inserted in the outer cylinder 2 and a plug body 6 to close the injection port 5 of the outer cylinder 2 in a liquidtight state. Then, the filling chambers 7A and 7B are filled with the injection from the filling holes 2A and 2B. Also, covering materials 8A and 8B to close the filling holes 2A and 2B are attached to the outer wall of the outer cylinder 2, thereby allowing the syringe 1 to be filled with the injection in an aseptic manner.