To provide a table leaf unit which has rigid strength though the structure is extremely light and can satisfy decoration requirements.

This table leaf unit (10) is equipped with a base panel (2), a top panel (3), and an edge part surrounding them. A honeycomb shape insert (5) made of paperboard is put in between the base panel (2) and the top panel (3) with rather thin wall thickness and a honeycomb shape air chamber (9) runs orthogonally against planes of the base panel (2) and the top panel (3). The honeycomb shape insert (5) is adhered, in this case, on the surfaces of the base panel (2) and the top panel (3). Thus, different from a conventional table leaf, a table leaf unit lighter by 50% in weight compared to an ordinary table leaf can be manufactured.