The present invention suppresses adhesion of a 
urea aqueous solution to an interior wall of an 
exhaust pipe and reduces flow resistance inside the 
exhaust pipe, in a 
urea aqueous solution mixing device. This 
urea aqueous solution mixing device is provided with an 
exhaust pipe (4B), an 
injector (5), a mixing 
pipe (6), an interior 
pipe (7), and a flow unit (20). The exhaust 
pipe (4B) has an 
elbow part (10) with a curved section, and a straight part (11). The 
injector (5) injects the urea aqueous solution, and is provided in the 
elbow part (10). The mixing pipe (6) is positioned so as to cover the area around the urea aqueous solution injected by the 
injector (5), and has an exit part formed between the interior walls of the exhaust pipe (4B) with an interval interposed therebetween, and a plurality of openings (6a) formed in the outer-
peripheral surface thereof. The interior pipe (7) allows 
exhaust gas to flow through the interior and outer-
peripheral sections thereof, and is positioned in the straight part (11) of the exhaust pipe (4B). The flow unit (20) guides 
exhaust gas into the interior pipe (7), and is formed between the exit part of the mixing pipe (6) and the interior walls of the exhaust pipe (4B).