An operation device for a vehicle in which an in-vehicle device (4,5,6) is controlled in accordance with an operation amount (θ) of an input unit which is manually operated by a driver, the operation device comprising: an operation unit that is displaceable along a predetermined operation trajectory by a manual operation of a driver; a displacement speed detection unit that detects a displacement speed (dθ) of the operation unit; a reaction force application unit that applies an operation reaction force to the operation unit for each predetermined operation amount (θ) of the operation unit; and a control unit that controls an operation reaction force applied by the reaction force application unit, wherein: the control unit changes the operation reaction force in accordance with a displacement speed (dθ) that is detected by the displacement speed detection unit, wherein the operation device further comprises a memory that stores an operation unit viscosity characteristic that has been set with an operation reaction force applied to the operation unit and a displacement speed (dθ) of the operation unit as parameters, wherein: the control unit changes the operation reaction force so that a load that acts on a driver at a time of operating the operation unit, which is determined by the operation unit viscosity characteristic and a muscle viscosity characteristic of a driver, becomes constant, characterized in that the operation unit viscosity characteristic is a characteristic that has a time constant such that when a displacement speed (dθ) is less than a reference displacement speed (Vα), the larger a displacement speed (dθ) is, the larger an operation reaction force becomes, and in that when a displacement speed (dθ) is equal to or greater than a reference displacement speed (Vα), an operation reaction force becomes constant regardless of a displacement speed (dθ). an operation unit that is displaceable along a predetermined operation trajectory by a manual operation of a driver; a displacement speed detection unit that detects a displacement speed (dθ) of the operation unit; a reaction force application unit that applies an operation reaction force to the operation unit for each predetermined operation amount (θ) of the operation unit; and a control unit that controls an operation reaction force applied by the reaction force application unit, wherein: the control unit changes the operation reaction force in accordance with a displacement speed (dθ) that is detected by the displacement speed detection unit, wherein the operation device further comprises a memory that stores an operation unit viscosity characteristic that has been set with an operation reaction force applied to the operation unit and a displacement speed (dθ) of the operation unit as parameters, wherein: the control unit changes the operation reaction force so that a load that acts on a driver at a time of operating the operation unit, which is determined by the operation unit viscosity characteristic and a muscle viscosity characteristic of a driver, becomes constant, characterized in that the operation unit viscosity characteristic is a characteristic that has a time constant such that when a displacement speed (dθ) is less than a reference displacement speed (Vα), the larger a displacement speed (dθ) is, the larger an operation reaction force becomes, and in that when a displacement speed (dθ) is equal to or greater than a reference displacement speed (Vα), an operation reaction force becomes constant regardless of a displacement speed (dθ). the control unit changes the operation reaction force in accordance with a displacement speed (dθ) that is detected by the displacement speed detection unit, wherein the operation device further comprises a memory that stores an operation unit viscosity characteristic that has been set with an operation reaction force applied to the operation unit and a displacement speed (dθ) of the operation unit as parameters, wherein: the control unit changes the operation reaction force so that a load that acts on a driver at a time of operating the operation unit, which is determined by the operation unit viscosity characteristic and a muscle viscosity characteristic of a driver, becomes constant, characterized in that the operation unit viscosity characteristic is a characteristic that has a time constant such that when a displacement speed (dθ) is less than a reference displacement speed (Vα), the larger a displacement speed (dθ) is, the larger an operation reaction force becomes, and in that when a displacement speed (dθ) is equal to or greater than a reference displacement speed (Vα), an operation reaction force becomes constant regardless of a displacement speed (dθ). the control unit changes the operation reaction force so that a load that acts on a driver at a time of operating the operation unit, which is determined by the operation unit viscosity characteristic and a muscle viscosity characteristic of a driver, becomes constant, characterized in that the operation unit viscosity characteristic is a characteristic that has a time constant such that when a displacement speed (dθ) is less than a reference displacement speed (Vα), the larger a displacement speed (dθ) is, the larger an operation reaction force becomes, and in that when a displacement speed (dθ) is equal to or greater than a reference displacement speed (Vα), an operation reaction force becomes constant regardless of a displacement speed (dθ).