A urea water supply guidance output device for a working vehicle includes: a urea water residual amount detection unit configured to detect a urea water residual amount in a urea water tank; an operation time measurement unit configured to measure an operation time of the working vehicle; a unit urea water consumption amount calculation unit configured to calculate a unit urea water consumption amount for each predetermined unit operation time; a urea water remaining time calculation unit configured to calculate an average urea water consumption amount and to calculate a urea water remaining time indicating a time to generation of urea water supply alarm; and an output processing unit configured to output guidance including the urea water remaining time when the urea water remaining time is a predetermined time or less.