A decentralized controller design approach is developed for the timed discrete event systems which are modelled by timed automata in this work. An approach, called augmentation, is presented to obtain the new modelling method such that each unit delay of any event represents a pair of new state and event. The augmented automata model, obtained by using this approach, is considered to design a decentralized controller. This controller design approach is developed such that the local controller is designed for each subautomaton, obtained by using overlapping decompositions and expansions and these controllers are then combined to obtain a decentralized controller for the given timed automaton. The designed decentralized controller guarantees the unreachability of a forbidden state in the considered automaton.