To weld an injection nozzle and a casing after pressing the injection nozzle into the casing so as to be able to adjust an electromagnetic gap efficiently with high accuracy.

A solenoid 12 and a core cylinder 10 are provided in a casing 22 of a fuel injection valve 21, and a needle valve 7 with an anchor 8 fixed thereto is provided in an injection nozzle 23. The injection nozzle 23 is pressed into the casing 22 so that an electromagnetic gap formed between the anchor 8 and core cylinder 10 has predetermined specified dimensions, and the casing 22 and the injection nozzle 23 are welded by a weld part 25.