A ring-shaped connecting portion is formed on a seat surface side of a pipe connector. The connecting portion is tapered so that thickness thereof gradually reduces toward a tip end thereof. A protrusion is formed on the tip end of the connecting portion. A ring-shaped groove is formed on a flat outer peripheral surface of a common rail. By fitting the protrusion into the groove, the connector can be positioned to a predetermined position of the common rail. In this structure, current can be concentrated to the protrusion and current density can be increased. As a result, sufficient bonding strength can be attained.
