PURPOSE: To provide stock data by which the stock of automobile parts can be grasped at every main warehouse and delivery vehicle and in which human mistakes are hard to occur and which are highly reliable, by transmitting, to a parent machine, goods - delivery and order receiving data registered at child machines, and conducting stock management in a lump at the parent machine.

CONSTITUTION: A parent machine 1 is equipped with an operation processing means 3; a data management means 4 to manage data accumulated at data memorizing means 4a, 4b; an output means 6 consisting of a printer device; and an outside communicating means 5 to receive data from each child machine 2. Each child machine 2 is equipped with a main processor 8; data memorizing means 8a, 8b, 8c; an output means 10 consisting of a printer device; and an outside communicating means 11 to transmit data to the parent machine 1. By connecting the outside communicating means 11 of each child machine 2 to the outside communicating means 5 of the parent machine 1, goods-delivery and order receiving data registered at each child machine 2 are transmitted to the parent machine 1, and stock management comes to be conducted in a lump at the parent machine 1.