A visual ability improvement device installed in a vehicle includes a noise generator, a surrounding situation detector, a driver status detector, a vehicle status detector, an operation switch, and a noise output device. A controller of the noise generator determines an optimum strength based on the surrounding situation from the surrounding situation detector, the driver's status from the driver status detector, the vehicle's status from the vehicle status detector, and the correspondence of the optimum representative noise to the above situation and statuses from the correspondence memory. Then the controller generates a noise with the determined the optimum representative noise strength, and outputs to the noise output device such as passenger compartment light a control signal which depends on the generated noise.