An upper revolving structure (3) includes a revolving frame (5), a floor member (9) which is provided on the revolving frame (5) and a front side of which serves as a footrest section (11) on which an operator rests his or her feet, a cab box (17) which forms an operating room (18) above the floor member (9), and an indoor unit (23) disposed on the floor member (9) to supply sucked air as conditioned air. A lower surface (11B) side of the footrest section (11) of the floor member (9) is formed as a unit mounting surface (12), and, as for the indoor unit (23), a box body (24) is disposed on the lower side of the unit mounting surface (12) and, in this state, the box body (24) is mounted on the unit mounting surface (12) by means of a plurality of bolts (32).