To provide a height regulating device having a separate height regulating mechanism part installable later and never fluctuating the steering property and comfortableness of the vehicle before and after the height regulation.

This device has a wheel suspension device part 121 and a height regulating mechanism part 120 serially arranged separately from the wheel suspension device part. The height regulating mechanism part 120 is formed of a body (housings 22, 23, 24) fixed to a body-side member 100, a rod 10 arranged in a manner as to be vertically movable relatively to the body and having the lower end fixed to the upper end of the wheel suspension device part, a driving mechanism 32 for vertically moving the rod relatively to the body part, a decelerating mechanism (a ring gear 27a, a planetary gear 28) connected to the driving mechanism, and an electric driving means (a motor 4) connected to the decelerating mechanism.