Construction machine

A construction machine having a working attachment, said construction machine comprising:

• a base frame for supporting said working attachment so as to be raised and lowered;
• an engine installed on said base frame;
• an exhaust gas after-treatment device to purify exhaust gas from said engine while the exhaust gas flows therethrough;
• and
• a guard panel installed over said base frame so as to cover said engine and said exhaust gas after-treatment device,
• wherein said exhaust gas after-treatment device includes a first treatment section having a filter to collect dust contained in the exhaust gas from said engine and a second treatment section having a catalyst for decomposing nitrogen oxides contained in the exhaust gas treated by said first treatment section,
• said guard panel includes a top plate, said top plate being disposed in parallel with said base frame and having an opening in a portion thereof corresponding to said engine, and a bonnet formed so as to project upwards from said top plate and cover said opening,
• one of said first and second treatment sections is disposed lower than said top plate, and at least a part of the other treatment section is disposed higher than said top plate through said opening and lower than said bonnet.