PURPOSE: To obtain a travelling machine having a great capability of ascending and descending stairs, and easily controlled, by providing respective wheels at ends of arm portions and a rotary central portion.

CONSTITUTION: When a wheel 6a comes into collision with a side surface of a first step 22a, such a collision is detected by a travel control mechanism 20, and a rotary arm body 3 is forwardly rotated by a drive mechanism 8. Accordingly, the rotary arm body 3 is upwardly rotated about the wheel 6a, and a wheel 6b is abutted against an upper surface of the first step 22a. Then, when the rotary arm body 3 is further rotated, it is upwardly rotated about the wheel 6b abutted against the upper surface of the first step 22a to be ascended to the first step 22a. Then, when the rotary arm body 3 is rotated at an angle of 120°, the rotation is stopped, and at the same time, the rotary arm body is unrotatably fixed, thereafter forwardly rotating the wheels 6a-6d to travel the arm body on the upper surface of the first step 22a. Subsequently, in the same manner as above, the arm body may ascend stairs 22 step by step.