PURPOSE: To reduce the entire height of a seat for two passengers as low as possible by combining a case-type holding member with two formed members in which formed rods for a passenger seat are arranged at the same height in parallel with each other.

CONSTITUTION: A molded rod 2 bridged across a plurality of support legs of a passenger seat has C-shape (in cross section) joint rails 5, 8 which are arranged side by side at the same height. The joint rails 5, 8 have paths 6, 7 individually which are used for jointing a holding leg traverse and a plate for mounting a seating part. A case-shape holding member 4 provided on the upper part of the joint rail 5 secures the strength of a formed rod 2, and a cover 9 provided on the upper part of the joint rail 8 protects an adjusting rail of the seating part from polluted materials. As a result, the entire height of a seat for passengers can be restrained as low as possible, and the initial safety in terms of strength cannot be impaired.