A work vehicle with a hydrostatic steering system is disclosed which is capable of performing optimum control of the absorption torque of a hydraulic pump according to running load; capable of preferentially ensuring turning performance and implement speed when running load is relatively low; and capable of ensuring desired turning performance even when running load is relatively high. To this end, a bulldozer with a hydrostatic steering system, wherein the power of a hydraulic motor driven by pressure oil fed from a hydraulic pump operated by an engine is transmitted to right and left crawler tracks through a differential steering means composed of planetary gear trains etc., is designed to control the absorption torque of the hydraulic pump according to the speed ratio of a torque converter calculated by a speed ratio operation unit.