MEASURING DEVICE AND MEASURING SYSTEM

OBJECT There are provided a measuring apparatus and a measuring system that can measure a distance between points and the like with high accuracy even on a narrow path that a vehicle can enter, and even if a road surface has bumps. SOLUTION Measuring devices 5 each include a rotating body 51 arranged between a wheel W for supporting a tire T and a wheel hub WH with rotation centers aligned with each other, and an optical detector 52 fixed to a body frame F. The rotating body 51 is formed of a disk portion 511 attached between the wheel W and a mounting surface of the wheel hub WH, and a cylindrical portion 512 extending from the disk portion 511 to the body frame F and encompassing an outer circumferential surface of the wheel hub WH. In a circumferential surface of the cylindrical portion 511, there are provided long holes 513 as light-transmitting portions that transmit light. The optical detector 52 includes a light-emitting element 521 serving as a light-emitting portion and a light-receiving element 522 serving as a light-receiving portion, which are fixed to the body frame F by a mounting bracket 523.