PROBLEM TO BE SOLVED: To provide a urea water consumption amount diagnosis device for urea SCR which can detect the normality and abnormality of urea water injection from a dosing valve.SOLUTION: The urea water consumption amount diagnosis device for the urea SCR comprises: consumption amount calculation means 32 for calculating a consumption amount from a detection value of an urea water sensor 22; injection amount indication means 30 for indicating an urea water amount from a dosing valve 12 according to NOx in an exhaust gas; indication injection amount integration means 31 for integrating an indication injection amount indicated at the injection amount indication means 30; and abnormality diagnosis means 33 for determining whether the urea water injection by the dosing valve 12 is normal or abnormal by comparing a determination amount when the integrated indication injection amount reaches a determination amount L and the integrated consumption amount. The abnormality diagnosis means 33 determines the pre
