A working vehicle comprising: an engine; a hydraulic pump that is driven by the engine; a traveling hydraulic motor that is driven by hydraulic fluid discharged from the hydraulic pump; a pump displacement control cylinder that changes a pump displacement of the hydraulic pump by changing a tilting angle of the hydraulic pump; a pilot hydraulic source that supplies hydraulic fluid for driving the pump displacement control cylinder; a pilot pressure control valve that controls a pilot pressure that is a pressure of hydraulic fluid supplied to the pump displacement control cylinder from the pilot hydraulic source; a motor displacement control part that changes a motor displacement of the traveling hydraulic motor by changing a tilting angle of the traveling hydraulic motor; and a drive circuit pressure detection part that detects a drive circuit pressure that is the pressure of hydraulic fluid supplied to the traveling hydraulic motor characterized by an upper limit speed setting part for setting a target upper limit speed for an upper limit variable speed control that limits an upper limit of vehicle speed to a speed lower than maximum vehicle speed; a speed range determination part that determines if the target upper limit speed is within a normal speed range in which the upper limit of vehicle speed is changed by changing a lower limit of motor displacement between minimum displacement and maximum displacement, or within a low speed range that is lower than the normal speed range; and an upper limit speed control part that controls the lower limit of motor displacement in conformance with the target upper limit speed through the motor displacement control part when the target upper limit speed is within the normal speed range and controls an upper limit of pilot pressure in conformance with the target upper limit speed through the pilot pressure control valve when the target upper limit speed is within the low speed range; wherein when the target upper limit speed is within the low speed range, the upper limit speed control part controls the pilot pressure control valve such that the upper limit of pilot pressure increases as the drive circuit pressure increases. an engine; a hydraulic pump that is driven by the engine; a traveling hydraulic motor that is driven by hydraulic fluid discharged from the hydraulic pump; a pump displacement control cylinder that changes a pump displacement of the hydraulic pump by changing a tilting angle of the hydraulic pump; a pilot hydraulic source that supplies hydraulic fluid for driving the pump displacement control cylinder; a pilot pressure control valve that controls a pilot pressure that is a pressure of hydraulic fluid supplied to the pump displacement control cylinder from the pilot hydraulic source; a motor displacement control part that changes a motor displacement of the traveling hydraulic motor by changing a tilting angle of the traveling hydraulic motor; and a drive circuit pressure detection part that detects a drive circuit pressure that is the pressure of hydraulic fluid supplied to the traveling hydraulic motor characterized by an upper limit speed setting part for setting a target upper limit speed for an upper limit variable speed control that limits an upper limit of vehicle speed to a speed lower than maximum vehicle speed; a speed range determination part that determines if the target upper limit speed is within a normal speed range in which the upper limit of vehicle speed is changed by changing a lower limit of motor displacement between minimum displacement and maximum displacement, or within a low speed range that is lower than the normal speed range; and an upper limit speed control part that controls the lower limit of motor displacement in conformance with the target upper limit speed through the motor displacement control part when the target upper limit speed is within the normal speed range and controls an upper limit of pilot pressure in conformance with the target upper limit speed through the pilot pressure control valve when the target upper limit speed is within the low speed range; wherein when the target upper limit speed is within the low speed range, the upper limit speed control part controls the pilot pressure control valve such that the upper limit of pilot pressure increases as the drive circuit pressure increases.