A work vehicle comprising: an engine; a variable displacement hydraulic pump driven by the engine; a work implement driven by hydraulic fluid discharged from the hydraulic pump; a pump displacement control device for controlling the displacement of the hydraulic pump; a pump pressure detector for detecting a discharge pressure from the hydraulic pump; a relief valve which opens when the discharge pressure from the hydraulic pump reaches or exceeds a prescribed relief pressure; a travel device allowing the vehicle to travel; a power transmission device into which drive power from the engine enters, so that the power transmission device outputs the drive power for driving the travel device; an accelerator operation member; a work implement operation member; and a controller for controlling the power transmission device; the controller including: a transmission requirement setting unit for setting a required traction force that is a target traction force for the travel device on the basis of an amount the accelerator operation member is operated; a work implement requirement setting unit for setting a required flow rate that is a target flow rate in the work implement on the basis of an amount the work implement operation member is operated; an engine requirement setting unit for determining the horsepower required from the engine on the basis of the horsepower required by the transmission set on the basis of the required traction force, and the horsepower required by the work implement set on the basis of the required flow rate; a required throttle setting unit for setting a commanded throttle value sent to the engine on the basis of the horsepower required from the engine; and a pump displacement setting unit for setting a target displacement for the hydraulic pump on the basis of the required flow rate; and the work implement requirement setting unit sets an upper limit for the required flow rate to a prescribed flow rate limit value when the discharge pressure of the hydraulic pump is at or above a prescribed pressure threshold. an engine; a variable displacement hydraulic pump driven by the engine; a work implement driven by hydraulic fluid discharged from the hydraulic pump; a pump displacement control device for controlling the displacement of the hydraulic pump; a pump pressure detector for detecting a discharge pressure from the hydraulic pump; a relief valve which opens when the discharge pressure from the hydraulic pump reaches or exceeds a prescribed relief pressure; a travel device allowing the vehicle to travel; a power transmission device into which drive power from the engine enters, so that the power transmission device outputs the drive power for driving the travel device; an accelerator operation member; a work implement operation member; and a controller for controlling the power transmission device; the controller including: a transmission requirement setting unit for setting a required traction force that is a target traction force for the travel device on the basis of an amount the accelerator operation member is operated; a work implement requirement setting unit for setting a required flow rate that is a target flow rate in the work implement on the basis of an amount the work implement operation member is operated; an engine requirement setting unit for determining the horsepower required from the engine on the basis of the horsepower required by the transmission set on the basis of the required traction force, and the horsepower required by the work implement set on the basis of the required flow rate; a required throttle setting unit for setting a commanded throttle value sent to the engine on the basis of the horsepower required from the engine; and a pump displacement setting unit for setting a target displacement for the hydraulic pump on the basis of the required flow rate; and the work implement requirement setting unit sets an upper limit for the required flow rate to a prescribed flow rate limit value when the discharge pressure of the hydraulic pump is at or above a prescribed pressure threshold. a transmission requirement setting unit for setting a required traction force that is a target traction force for the travel device on the basis of an amount the accelerator operation member is operated; a work implement requirement setting unit for setting a required flow rate that is a target flow rate in the work implement on the basis of an amount the work implement operation member is operated; an engine requirement setting unit for determining the horsepower required from the engine on the basis of the horsepower required by the transmission set on the basis of the required traction force, and the horsepower required by the work implement set on the basis of the required flow rate; a required throttle setting unit for setting a commanded throttle value sent to the engine on the basis of the horsepower required from the engine; and a pump displacement setting unit for setting a target displacement for the hydraulic pump on the basis of the required flow rate; and the work implement requirement setting unit sets an upper limit for the required flow rate to a prescribed flow rate limit value when the discharge pressure of the hydraulic pump is at or above a prescribed pressure threshold.