CONSTRUCTION MACHINE

摘要

[PROBLEMS] A construction machine where the temperature of a reduction agent in a reduction agent tank is controlled by a reduced number of parts and without installing a heat exchanger in the reduction agent tank. [MEANS FOR SOLVING PROBLEMS] The construction machine has a front working device driven by an engine (4), a urea SCR catalyst (20) placed in an exhaust route (19) of the engine (4) and reducing and purifying nitrogen oxides in exhaust gas, a urea water tank (23) for containing urea water supplied to the exhaust route (19), a temperature detector (24) for detecting the temperature of the urea water in the urea water tank (23), an air conditioner (21) for air conditioning an operation room (3), and warm/cold air guidance means for guiding, according to the temperature of the urea water detected by the temperature detector (24), warm/cold air ejected from the air conditioner (21) to the urea water tank (23). The warm/cold air guidance means includes a controller (31) for outputting, as a control signal, a cold air signal and a warm air signal corresponding to the temperatures of cold air and warm air ejected from the air conditioner (21).