This paper describes the architecture of a prototype of a unit (module robot) for a multi-agent mobile system. Every unit is aimed at composing a walking robot as a whole, and employs a parallel link manipulator for its locomotive-leg with an ARM processor-based local controller. The details of both hardware and software of the unit would be presented for the readers' reference. The simulation and experimental results would be shown to provide the feasibility study over the prototype unit, followed by a discussion of the future work for the target mobile system.