An experimental model and a prototype model were made for development of underwater inspection robot. The experimental model is overground test robot that is not made watertight. The model was used for basic research and a debug tool for program development. The prototype model made watertight was developed after tests of the experimental model. The model is the first walking robot in the world that has succeeded in walking on seabed. The hardware and software of the robots are described herein. The principal features of the models are as follows. The robots are six-legged articulated insect type robots known as AQUAROBOT. Each leg has three articulations and is driven semi-directly by a DC motor that is built in the leg and has a touch sensor on the foot. The robots can walk on uneven ground and can walk in any direction without changing its quarter.