To make high lift inspection on the wall surfaces of a larger steel construction in a boiler furnace or the like, at high mobility and efficiency, by combining a lightweight, small-sized magnetic crawler robot and a boom.

A high lift inspection instrument comprises a robot controller 2 for specifying the travel motion of a magnetic crawler robot 3 at the moving point, a telescopic boom 11 for supporting the robot 3, telescopic arms 12 all for supporting the main body of the boom 11 to vary the angle of elevation thereof, a rotary base 13 on which one-side ends of the boom 11 and arms 12 are raised, and a boom controller 14 for driving the boom 11, arms 12 and base 13 on the basis of the positional information of the robot 3 sent from the robot controller 2 to thereby control the position of the mounting tip of the boom 11 in accordance with the successive displacement of the robot 3 running. The mounting tip of the boom 11 that supports the robot 3 running is made to follow the movement of the robot 3.