Construction machine

A construction machine comprising:

• an automotive lower traveling structure (2);
• an upper revolving structure (3) rotatably mounted on said lower traveling structure (2);
• a working mechanism (4) provided capable of moving upward/downward on said upper revolving structure (3);
• and
• a counterweight (5) provided on the rear side of said upper revolving structure (3) in order to keep balance with said working mechanism (4), wherein
• said upper revolving structure (3) is provided with a revolving frame (6) forming a support structural body, a floor member (10, 31) provided on said revolving frame (6) and having the rear side as a seat base (11, 32) on which an operator's seat (17) is mounted and the front side as a flat-plate shaped footrest area (12, 33) on which an operator places a foot, a cab box (20) provided covering a periphery and an upper part of said floor member (10, 31) and forming an occupying space (21) inside, and an indoor unit (22) of an air conditioning unit mounted on said floor member (10, 31) and supplying sucked air to said occupying space (21) as conditioning air;
• characterized in that:
• said seat base (11, 32) of said floor member (10, 31) has a rear surface plate (11C, 32C) rising from a rear end of said footrest area (12, 33) and extending in a left-right direction, an operator's seat mounting plate (11D, 32D) provided on an upper end of said rear surface plate (11C, 32C) and extending in the front-rear direction and on which said operator's seat (17) is mounted, and a duct accommodating space (14, 35) formed in the vertical direction among said rear surface plate (11C, 32C), said operator's seat mounting plate (11D, 32D), and said footrest area (12, 33);
• an indoor air inlet duct (23, 38) having the front surface side opened as a filter fitting hole (25, 40) and introducing air in said occupying space (21) toward said indoor unit (22) is provided in said duct accommodating space (14, 35);
• and
• an indoor air filter (26, 41) for catching dusts in the air is provided on said filter fitting hole (25, 40) of said indoor air inlet duct (23, 38).