Abstract: A switch controlling apparatus for small capacitance ATM exchange comprises Line Interface Modules having a plurality of buffers for storing cell data inputted from an outside apparatus, and a plurality of self order comparators for determining whether the cell data through a contorl bus from a switch module is mine and producing an enable signal when the cell data is determined to mine. It is possible to connect sequentially a plurality of LIMs to the switch module at integer times rate of input cell rate, to simplify the structure of the apparatus of the present invention and thereby to realize stable data communication.