A construction machine comprising: an automotive lower traveling structure; an upper revolving structure which is revolvably loaded on said lower traveling structure; and a working mechanism which is tiltably provided on the front side of said upper revolving structure at an intermediate position in a left-right direction, wherein said upper revolving structure is equipped with a revolving frame located on the front side and provided with mounting brackets (5B1, 5C1) adapted to mount said working mechanism to the intermediate position in the left-right direction via a connecting pin, and a fuel tank a front end of which is located more rearward than said mounting brackets (5B1, 5C1) of said revolving frame and which is arranged by being put aside to one side in the left-right direction of said revolving frame, characterized in that: a first accommodating case (13, 31) which is located more forward than said fuel tank and is small in height dimension (H1, H4) of an upper surface (13E, 31E) is provided on one side in the left-right direction of said revolving frame, a second accommodating case (16, 33) the position of an upper surface (16E, 33E) of which is higher than said upper surface (13E, 31E) of said first accommodating case (13, 31) and lower than an upper surface of said fuel tank is provided on the rear side of said upper surface (13E, 31E) of said first accommodating case (13, 31) or between said first accommodating case (13, 31) and said fuel tank, an article accommodating space (17, 32) for accommodating articles (23, 24)is defined in one accommodating case of said first accommodating case (13, 31) and said second accommodating case (16, 33), and a reducing agent tank (20, 35) which is located in a tank accommodating space (15, 34) and stores a liquid reducing agent is provided in the other accommodating case of said first accommodating case (13, 31) and said second accommodating case (16, 33), wherein a first cover (13H, 31H) for opening/closing an opening (13G, 31G) is provided on said first accommodating cover (13, 31), and a second cover (16H, 33H) for opening/closing an opening (16G, 33G) is provided on said second accommodating case (16, 33). an automotive lower traveling structure; an upper revolving structure which is revolvably loaded on said lower traveling structure; and a working mechanism which is tiltably provided on the front side of said upper revolving structure at an intermediate position in a left-right direction, wherein said upper revolving structure is equipped with a revolving frame located on the front side and provided with mounting brackets (5B1, 5C1) adapted to mount said working mechanism to the intermediate position in the left-right direction via a connecting pin, and a fuel tank a front end of which is located more rearward than said mounting brackets (5B1, 5C1) of said revolving frame and which is arranged by being put aside to one side in the left-right direction of said revolving frame, characterized in that: a first accommodating case (13, 31) which is located more forward than said fuel tank and is small in height dimension (H1, H4) of an upper surface (13E, 31E) is provided on one side in the left-right direction of said revolving frame, a second accommodating case (16, 33) the position of an upper surface (16E, 33E) of which is higher than said upper surface (13E, 31E) of said first accommodating case (13, 31) and lower than an upper surface of said fuel tank is provided on the rear side of said upper surface (13E, 31E) of said first accommodating case (13, 31) or between said first accommodating case (13, 31) and said fuel tank, an article accommodating space (17, 32) for accommodating articles (23, 24)is defined in one accommodating case of said first accommodating case (13, 31) and said second accommodating case (16, 33), and a reducing agent tank (20, 35) which is located in a tank accommodating space (15, 34) and stores a liquid reducing agent is provided in the other accommodating case of said first accommodating case (13, 31) and said second accommodating case (16, 33), wherein a first cover (13H, 31H) for opening/closing an opening (13G, 31G) is provided on said first accommodating cover (13, 31), and a second cover (16H, 33H) for opening/closing an opening (16G, 33G) is provided on said second accommodating case (16, 33). a first accommodating case (13, 31) which is located more forward than said fuel tank and is small in height dimension (H1, H4) of an upper surface (13E, 31E) is provided on one side in the left-right direction of said revolving frame, a second accommodating case (16, 33) the position of an upper surface (16E, 33E) of which is higher than said upper surface (13E, 31E) of said first accommodating case (13, 31) and lower than an upper surface of said fuel tank is provided on the rear side of said upper surface (13E, 31E) of said first accommodating case (13, 31) or between said first accommodating case (13, 31) and said fuel tank, an article accommodating space (17, 32) for accommodating articles (23, 24)is defined in one accommodating case of said first accommodating case (13, 31) and said second accommodating case (16, 33), and a reducing agent tank (20, 35) which is located in a tank accommodating space (15, 34) and stores a liquid reducing agent is provided in the other accommodating case of said first accommodating case (13, 31) and said second accommodating case (16, 33), wherein a first cover (13H, 31H) for opening/closing an opening (13G, 31G) is provided on said first accommodating cover (13, 31), and a second cover (16H, 33H) for opening/closing an opening (16G, 33G) is provided on said second accommodating case (16, 33).