PURPOSE: To parallelly perform a receiving process for article order data registered on a handy terminal and a process for checkout operation that the cash registering device originally performs without any hindrance to the processes.

CONSTITUTION: When inputting a generated interruption signal from a radio part interface, a CPU 11 receives the article order data from the handy terminal 1 via a radio part 2 and stores them in an order file together with an added slip number, and sends the data to printers 4 and 5 through an in-line network 7. When a slip number is inputted from a keyboard, on the other hand, the corresponding article order data are read out of the order file and sales data are registered according to the article order data. The CPU performs those processes on a multitask basis.