PURPOSE: To achieve a high efficiency of work at a high place in an inclined ground or an irregular ground by installing levelling means capable of expansion freely to a plural crawler type running means respectively, supporting a mina body by the levelling means through an enlargement means, and installing a work platform at the main body to move up and down freely.

CONSTITUTION: Four crawler type means 1 are disposed under a main body 7, an inclination of the main body is detected by an inclination angle sensor 7a, obtained data are sent to a levelling control computing means 7b, and expansion of four levelling means 2 is adjusted to set the main body 7 horizontal, so a work platform 5 is stabilized. The width of crawlers is set large for stabilizing the work platform 5 at a work site. An adjustment point 4a is moved by a hydraulic cylinder by an oil pressure supplied from the mina body 7 to adjust the height of the platform 5. Expansion action of a width expanding means 3 is achieved by expanding a jack-up means 8 from under the main body 7 by an oil pressure to lift one side of the main body 7 just a little from the ground.