A self-propelled working vehicle comprises a front wheel unit, a rear wheel unit including a left rear wheel and a right rear wheel, and a drive transmission apparatus for transmitting drive from an engine to the rear wheel unit. The drive transmission apparatus includes a first drive transmission mechanism for transmitting the drive to the left rear wheel and a second drive transmission mechanism for transmitting the drive to the right rear wheel. The first transmission mechanism is arranged at the left side of the vehicle body, while the second transmission mechanism is arranged at the right side of the vehicle body. A brake assembly is arranged between the first drive transmission mechanism and the second drive transmission mechanism for acting on an output shaft of a first transmission unit and an output shaft of a second transmission unit. The first and second transmission units act as first and second change speed devices, respectively, which are operable independently of each other.