To provide a metering device, and a seal element and a valve needle used in the metering device, which can be manufactured more easily and more economically.

The valve needle 5, 6 having a valve needle shaft 5 penetrates a chamber containing compressed fluid in a housing 8. The valve needle shaft comprises a first end part 5a for operating in cooperation with an actuator assembly outside the chamber and a second end part 5b for controlling opening/closing of a metering opening. The seal element 1 is used as a penetration element for the first end part 5a of the valve needle shaft penetrating from the inside of the chamber 9 to the outside 10. The internal pressure is higher than the external pressure, the chamber 9 is sealed against the outside 10, and the seal element 1 is sealingly coupled with the valve needle 5 metal to metal without any welded part.