A front-mount mower tractor including a front axle case, a driver's platform disposed above the front axle case and in a front region of the tractor, a platform support frame having one end thereof fixed to the front axle case and extending under the driver's platform longitudinally forwardly of the tractor, and a mower unit raising and lowering link mechanism. The mower unit raising and lowering link mechanism includes lift links pivotally connected to the front axle case for suspending a mower unit from free ends thereof, lift arms pivotally connected to the front axle case above the lift links, at least a portion of each lift arm extending along a side surface of the platform support frame, connecting links each pivotally connected at one end thereof to one of the lift arms, and at the other end to one of the lift links, at least a portion of each connecting link extending along a side surface of the platform support frame, and a cylinder for swinging the right and left lift arms.