PURPOSE: To make a titled device run smoothly along a body to be inspected, by a ring-like driving part which runs in the axial direction along a track having the same bend as a pipe of the body to be inspected.

CONSTITUTION: Tracks 21A, 21B having the same bend as a pipe 20 are fitted onto the pipe 20 by a ring 22. A driving device 25 fitted to the tracks 21A, 21B by rollers 26W29 has a double ring structure consisting of rings 25A, 25B. On the ring 25A, a motor 31 is provided, its rotating force is transmitted to a sprocket 32, it is engaged with a chain 33 of the track 21A, and the ring 25A runs along the track 21A. Other motor 34 of the ring 25A is engaged with a rack of the ring 25B through a pinion 35, and the ring 25B is made to run along the circumference of the pipe 20. To the ring 25B, a probe 37 is fitted, and it is pressed against the surface of the pipe 20 by a spring 38.