An improvement is realized in mutual assembly strength between a swing bearing member and right and left longitudinal ribs, and welds are subjected to a reduced stress concentration. A backhoe comprises a swivel deck (10); a first longitudinal rib (19L) disposed on the swivel deck, the first longitudinal rib extending in a fore and aft direction, and having a front portion (19La) extending in a transverse direction; a second longitudinal rib (19R) disposed on said swivel deck, the second longitudinal rib extending in the fore and aft direction, and having a front end thereof connected to the front portion of the first longitudinal rib; and a swing bearing member (20) attached to a front surface of the front portion of the first longitudinal rib for supporting a ground working implement through a swing shaft.