An accelerator pedal device comprising: an accelerator pedal on a vehicle; an operation quantity detector for detecting an operation quantity of the accelerator pedal; an actuator for applying a reaction force to the accelerator pedal; a reaction force controller for controlling the actuator; and a travel controller for controlling the generation of a driving force and a braking force for the vehicle; wherein the travel controller generates the braking force if the operation quantity is smaller than a first threshold value; the travel controller generates the driving force if the operation quantity is greater than a second threshold value which is greater than the first threshold value; the travel controller generates neither the driving force nor the braking force thereby to allow the vehicle to travel by inertia if the operation quantity is greater than the first threshold value and smaller than the second threshold value; the first threshold value and the second threshold value comprise threshold values for the operation quantity for switching between traveling states of the vehicle; the first threshold value is a value at a boundary between a regenerative zone and a neutral zone; and the second threshold value is a value at a boundary between the neutral zone and a power zone, characterised in that the accelerator pedal device further comprises: an operating speed detector for detecting an operating speed of the accelerator pedal; wherein the travel controller increases the first threshold value and/or reduces the second threshold value if the operating speed exceeds a threshold value therefor for judging a degree of acceleration or deceleration of the vehicle. an accelerator pedal on a vehicle; an operation quantity detector for detecting an operation quantity of the accelerator pedal; an actuator for applying a reaction force to the accelerator pedal; a reaction force controller for controlling the actuator; and a travel controller for controlling the generation of a driving force and a braking force for the vehicle; wherein the travel controller generates the braking force if the operation quantity is smaller than a first threshold value; wherein the travel controller generates the braking force if the operation quantity is smaller than a first threshold value; the travel controller generates the driving force if the operation quantity is greater than a second threshold value which is greater than the first threshold value; the travel controller generates neither the driving force nor the braking force thereby to allow the vehicle to travel by inertia if the operation quantity is greater than the first threshold value and smaller than the second threshold value; the first threshold value and the second threshold value comprise threshold values for the operation quantity for switching between traveling states of the vehicle; the first threshold value is a value at a boundary between a regenerative zone and a neutral zone; and the second threshold value is a value at a boundary between the neutral zone and a power zone, the accelerator pedal device further comprises: an operating speed detector for detecting an operating speed of the accelerator pedal; wherein the travel controller increases the first threshold value and/or reduces the second threshold value if the operating speed exceeds a threshold value therefor for judging a degree of acceleration or deceleration of the vehicle. an operating speed detector for detecting an operating speed of the accelerator pedal; wherein the travel controller increases the first threshold value and/or reduces the second threshold value if the operating speed exceeds a threshold value therefor for judging a degree of acceleration or deceleration of the vehicle.