A four wheel drive front mower having a grass cutting unit connected to the front of a vehicle body. This mower comprises a hydrostatic transmission, an auxiliary change speed gearing, and a propelling drive transmission. The propelling drive transmission includes a center differential for distributing output of the auxiliary change speed device to front wheels and rear wheels, a clutch for making and breaking drive transmission from the center differential to the front wheels, and a front differential for transmitting the drive from the clutch to right and left front axles. The center differential, clutch and front differential are arranged vertically and serially.