PURPOSE: To lower machining accuracy required for valve parts by separately comprising a valve disk and an armature designed to drive the disk, and by fitting both the disk and armature through an irregular surface and hence automatically aligning both the valve disk and armature.

CONSTITUTION: The sphere surface 41 of a valve disk 30 is pressed to a seal surface 32 of a valve housing 28 with an energetic force of a spring 38 provided an armature 35 which is stronger than that of a spring 33 provided for a valve disk 30. With this construction, even if the axial center of a seal surface 32 of an injection nozzle 31 is deviated from the axial center of a connecting rod 36 for the armature 35, the pressing force of the spring 38 through the connecting rod 36 is equally exerted on the circumference between a sphere surface 41 and the seal surface 32 of the valve disk 30 automatically aligned, so as to secure seating status, because the contact between the connecting rod 36 and the valve disk 30 is R-surfaced and the contact surface of the valve disk 30 to the seal surface 32 is shaped like the sphere surface 41.