A construction machine where an operating load is transferred to a
location having good rigidity, thereby ensuring the strength of a vehicle
body and increasing the load-withstanding strength in relation to running
loads. The frame of the lower traveling body of the construction machine
comprising a hollow center frame having an upper plate with an attachment
ring, a lower plate, and side plates that surrounding sides of the frame
and that jut out from the attachment ring, and reinforcing ribs which
connect the upper plate to the lower plate in the interior of the center
frame beneath the attachment ring.