An informing device is an informing device mounted on a work vehicle that includes a lower base body, and a swivel body swivelably provided at the lower base body. The informing device includes a first detection unit that detects the actual amount of rotation of a drive device which swivels the swivel body or a driven part driven by the drive device, and a notification unit that issues a notification regarding information corresponding to the amount of rotation detected by the first detection unit.