A tubular member has one end inserted in a fluid passage of a passage member through an insertion hole. The tubular member includes a large diameter portion and a small diameter portion therebetween having a step defining an inclined portion. The inclined portion is inclined from the radially outside toward the radially inside. A lock member is held by a holding portion located outside the insertion hole relative to the radial direction of the insertion hole. The lock member urges the inclined portion radially inward and applies force to the inclined portion in the axial direction to cause the outer surface of the tubular member to urge a regulating portion to cause the regulating portion to restrict movement of the tubular member in the axial direction.