An in-vehicle actuator control method for controlling an operation of an in-vehicle actuator which is a noise source, comprising: - a road noise value estimating step (244, 245) of estimating a road noise value that quantifies a magnitude of a road noise from an angular acceleration of a wheel of a vehicle; - an estimation state determining step of determining whether or not an estimation state of the road noise value is a proper estimation state; - a background noise state determining step of determining whether a background noise of the vehicle is in a high background noise state in which the background noise of the vehicle is relatively large or a low background noise state in which the background noise of the vehicle is relatively small based on the road noise value and the estimation state; and - an output adjusting step (27, 28) of adjusting an output of the in-vehicle actuator according to a determined background noise state of the vehicle, wherein: - in the background noise state determining step: - it is determined whether a background noise of the vehicle is in the high background noise state or the low background noise state according to magnitudes of the road noise value and a predetermined threshold value when it is determined that the estimation state is the proper estimation state, and - it is determined that a background noise of the vehicle is in the low background noise state regardless of the road noise value when it is determined that the estimation state is not the proper estimation state; and - in the output adjusting step (27, 28): - an output of the in-vehicle actuator is set so that a noise accompanying an operation of the in-vehicle actuator becomes relatively large when it is determined that the background noise of the vehicle is in the high background noise state, and - an output of the in-vehicle actuator is set so that a noise accompanying an operation of the in-vehicle actuator becomes relatively small when it is determined that the background noise of the vehicle is in the low background noise state, and - in the estimation state determining step, it is determined that an estimation state of the road noise value is not the proper estimation state when the wheel is slipping. - a road noise value estimating step (244, 245) of estimating a road noise value that quantifies a magnitude of a road noise from an angular acceleration of a wheel of a vehicle; - an estimation state determining step of determining whether or not an estimation state of the road noise value is a proper estimation state; - a background noise state determining step of determining whether a background noise of the vehicle is in a high background noise state in which the background noise of the vehicle is relatively large or a low background noise state in which the background noise of the vehicle is relatively small based on the road noise value and the estimation state; and - an output adjusting step (27, 28) of adjusting an output of the in-vehicle actuator according to a determined background noise state of the vehicle, - in the background noise state determining step: - it is determined whether a background noise of the vehicle is in the high background noise state or the low background noise state according to magnitudes of the road noise value and a predetermined threshold value when it is determined that the estimation state is the proper estimation state, and - it is determined that a background noise of the vehicle is in the low background noise state regardless of the road noise value when it is determined that the estimation state is not the proper estimation state; and - it is determined whether a background noise of the vehicle is in the high background noise state or the low background noise state according to magnitudes of the road noise value and a predetermined threshold value when it is determined that the estimation state is the proper estimation state, and - it is determined that a background noise of the vehicle is in the low background noise state regardless of the road noise value when it is determined that the estimation state is not the proper estimation state; and - in the output adjusting step (27, 28): - an output of the in-vehicle actuator is set so that a noise accompanying an operation of the in-vehicle actuator becomes relatively large when it is determined that the background noise of the vehicle is in the high background noise state, and - an output of the in-vehicle actuator is set so that a noise accompanying an operation of the in-vehicle actuator becomes relatively small when it is determined that the background noise of the vehicle is in the low background noise state, and - an output of the in-vehicle actuator is set so that a noise accompanying an operation of the in-vehicle actuator becomes relatively large when it is determined that the background noise of the vehicle is in the high background noise state, and - an output of the in-vehicle actuator is set so that a noise accompanying an operation of the in-vehicle actuator becomes relatively small when it is determined that the background noise of the vehicle is in the low background noise state, and - in the estimation state determining step, it is determined that an estimation state of the road noise value is not the proper estimation state when the wheel is slipping.