A driving device for a wheelbarrow includes a motor assembly which has a shaft and a driving gear is connected to the shaft. The driving gear is engaged with planet gears of a gear set to drive a collar which is connected to a rim with a tire connected to the rim. Therefore, the wheel rotates when the motor assembly is activated. A brake mechanism an adjustment nut which is threadedly connected to a motor frame of the motor assembly such that when the user pulls a brake lever, the adjustment nut is moved to shift a brake lining to brake the wheel.