The concreter placing method using a pump equipped with pipes and an end-hose has been used extensively. But placing concrete is still, in general, one of the most labor intensive in construction. The Horizontal Concrete Distributor has solved diverse problems involved in moving the end-hose and relocating pipes. This robot mechanizes feed hose-nozzle relocation to improve the working environment as well as to save labor in concrete placing works. The robot is a large manual manipulator with an overall length of 20meters and four horizontally bendable articulation. The operating system of the robot is intelligent and sufficiently flexible to respond to any command given by the operator regarding direction of movement. The direction of movement of the nozzle can be input by a single universal lever. When the input is made, the computer determines the shape of the robot so that the nozzle can avoid obstacles such as columns in the vicinity, and the system controls the movement with 4 actuators. The development of both the automatic nozzle positioner and automatic obstacle avoidance system has greatly improved the safety and the operability of the Horizontal Concrete Distributor, while contributing toward largely improving concrete placing works.