To provide a fuel injection valve and its injection quantity regulating method which can be easily processed having a small number of parts, and which can regulate injection quantity in a short time.

A fixed core 30 is fixed to a cylindrical member 12 by being pressed and inserted to a nonmagnetic member 14 of the cylindrical member 12, and inside of a secondary magnetic member 15. An inner diameter wall of the fixed core 30 has a larger diameter part 35, and a smaller diameter part 36 which has a smaller inside diameter than the larger diameter part 35 in this order from the movable core 22 side. A step 37 is formed on the border between the larger diameter part 35 and the smaller diameter part 36. One end of a spring 24 is engaged with the step 37 and the other end is engaged with the movable core 22. The spring 24 energizes the movable core 22 and a valve member 20 in the direction which the valve member 20 is seated at a valve seat 17. When energization to a coil 44 is on, the valve member 20 along with the movable core 22 is moved to the fixed core 30 against the energization of the spring 24, and a contact 21 is separated from the valve seat 17. Thus, the fuel is injected from an injection hole 18a.