For the decommissioning work for Fukushima Daiichi nuclear power plant, there is the need for robots which can inspect a high place in plant. In this study, we suggest crank-wheel robot equipped with expansion boom. Crank-wheel has toughness and high mobility in a location of stairs and obstacles but it is too long to rotate in narrow space because of its long crank-leg. In order to solve that, we developed the "bending crank-leg" which can become shorter than the conventional one by bending. In inspection system, we made high rigidity boom consists of CFRP pipe. It can be expanded to 3m by air pressure and adjusted length by an internal wire. The reel mechanism we developed has auto winding system by which the boom can be stored in an emergency.