The Chi calculus is obtained from the π calculus by unifying two classes of restricted names. The polyadic Chi calculus extends Chi calculus in that more than one pieces of information can be passed around in a communication. And the atomic Chi calculus is the subcalculus of the polyadic Chi calculus by removing the prefix combinatory. In this paper, the bisimulation equivalences for the atomic Chi calculus are investigated. The main result of this paper is that, in a certain sense, there is only one bisimulation equivalence on the atomic Chi processes.