A working machine comprising: a machine body; a steering device capable of changing an orientation of the machine body; a front wheel disposed at a front portion of the machine body and a steering angle of which is changeable by the steering device; a first wheel (7R1) which is a first rear wheel disposed at a rear portion of the machine body; a second wheel (7R2) which is a second rear wheel disposed at the rear portion of the machine body and separated from the first wheel (7R1) in a machine-body width direction; a rotational difference generating device that causes a rotational difference between the first wheel (7R1) and the second wheel (7R2); a controller having a first control unit (40a1) that sets a steering angle of the steering device based on a planned traveling route, and a second control unit (40a2) that controls the rotational difference generating device based on the planned traveling route to cause a rotational difference between the first wheel (7R1) and the second wheel (7R2); and a transmission that performs speed-shifting and is switchable between equal speed drive in which both the front wheel and the first and second rear wheels are driven at an equal speed and increased speed drive in which the front wheel is driven faster than the first and second rear wheels, wherein the rotational difference generating device is a braking device that causes a rotational difference between the first wheel (7R1) and the second wheel (7R2) by switching between a brake state in which at least one of the first wheel (7R1) and the second wheel (7R2) is braked and a release state in which the at least one of the first wheel (7R1) and the second wheel (7R2) is not braked, and wherein the second control unit (40a2), based on the planned traveling route, causes the braking device to perform setting about braking of either the first wheel (7R1) or the second wheel (7R2) by performing pumping control in which switching between the brake state and the release state is repeated, and sets either a cycle at which the brake state and the release state are switched in the pumping control or a duty ratio at which the brake state is performed in the cycle, characterized in that the second control unit (40a2) sets the duty ratio to be different between the equal speed drive and the increased speed drive. a machine body; a steering device capable of changing an orientation of the machine body; a front wheel disposed at a front portion of the machine body and a steering angle of which is changeable by the steering device; a first wheel (7R1) which is a first rear wheel disposed at a rear portion of the machine body; a second wheel (7R2) which is a second rear wheel disposed at the rear portion of the machine body and separated from the first wheel (7R1) in a machine-body width direction; a rotational difference generating device that causes a rotational difference between the first wheel (7R1) and the second wheel (7R2); a controller having a first control unit (40a1) that sets a steering angle of the steering device based on a planned traveling route, and a second control unit (40a2) that controls the rotational difference generating device based on the planned traveling route to cause a rotational difference between the first wheel (7R1) and the second wheel (7R2); and a transmission that performs speed-shifting and is switchable between equal speed drive in which both the front wheel and the first and second rear wheels are driven at an equal speed and increased speed drive in which the front wheel is driven faster than the first and second rear wheels, wherein the rotational difference generating device is a braking device that causes a rotational difference between the first wheel (7R1) and the second wheel (7R2) by switching between a brake state in which at least one of the first wheel (7R1) and the second wheel (7R2) is braked and a release state in which the at least one of the first wheel (7R1) and the second wheel (7R2) is not braked, and wherein the second control unit (40a2), based on the planned traveling route, causes the braking device to perform setting about braking of either the first wheel (7R1) or the second wheel (7R2) by performing pumping control in which switching between the brake state and the release state is repeated, and sets either a cycle at which the brake state and the release state are switched in the pumping control or a duty ratio at which the brake state is performed in the cycle, based on the planned traveling route, causes the braking device to perform setting about braking of either the first wheel (7R1) or the second wheel (7R2) by performing pumping control in which switching between the brake state and the release state is repeated, and sets either a cycle at which the brake state and the release state are switched in the pumping control or a duty ratio at which the brake state is performed in the cycle, characterized in that the second control unit (40a2) sets the duty ratio to be different between the equal speed drive and the increased speed drive.