An ATM transmitter distributes an ATM transmission process function to plural electronic circuit packages and performs transmission process by forming routes between the plural circuit packages. The routes can be flexibly varied while a configuration of a variety of process functions are managed. The cell distribution section which has plural input and output terminals connected to respective electronic circuit packages forms a route among respective ones of the arbitrary input and output terminals so that receive ATM cells are input and output between respective electronic circuit packages. Process functions are arranged for each electronic circuit package. The function configuration of all the electronic circuit packages is previously set. Thus, a route formation is indicated to the cell distribution section. In other case, input and output terminals for each route are sequentially arranged along the route. The control order of receive ATM cells is previously set. Thus, a receive ATM cell transmission process is performed by the cell distribution section. Moreover, the number of times ATM cells are input and output is arranged for each input and output terminal so that the cell distribution section repeats an input and output operations to the same input and output terminal.