To widely secure a space at the feet of an operator by positioning an attaching member attaching a travelling operation valve downward from the upper face of a floor plate mounting a cab and integrating it with the floor plate.

A travelling operation valve 4 controlling the travelling of a hydraulic shovel is attached to be positioned frontward of the operator seat 2 of a cab 12 and a flange-like attaching part 4 is attached to be positioned downward from the upper face of a floor plate 16. The floor plate 16 is made of a steel plate, and a rectangular opening 16a is formed. A valve support 17 folds the strip steel plate of the same width as the horizontal width of the opening 16a on longitudinal both ends at the right angles, is formed in the form of a channel, and a rectangular through hole is formed on the center part. Both the ends of the valve support 17 are integrally provided to be welded on the lower face of the floor part 16, and part of an attaching part 4a is arranged so that it is overlapped on the frame 12a of the cab 12 in planar view. Thereby, the travelling operation valve 4 is biased to the frame 12a, and a space at the feet of an operator can be secured widely.