This vehicle-mounted device is a vehicle-mounted device mounted on a vehicle that has a body and a steering unit supported on the body via a steering shaft, and includes a user interface, camera, or antenna attached to the steering unit; a first sensor unit that is attached to the body and detects a first angular velocity or a first acceleration as a first detection value; and a calculation device that performs calculation based on the first detection value and is connected to the user interface, camera, or antenna.