PURPOSE: To efficiently perform synchronizing control for a communication test, to reduce the load of an operation and time loss at the time of test execution and to improve operability and inspection accuracy for the communication test by automatically performing setting and synchronizing control on the transmission side and reception side.

CONSTITUTION: Two communication equipments 1 and 7 to perform counter operation tests are respectively composed of instruction processing parts 2 and 8, main storage parts 3 and 9, channel control parts 4 and 10 and line control parts 5 and 11 and connected by communication cables 100-10n. Then, communication programs 6 and 12 stored in the respective main storage parts 3 and 9 transmit transmitting data for synchronizing, set the address of the transmission source to the destination address of data for synchronizing to be next transmitted at the time of data reception, send it back, establish synchronism by receiving white data with these sent back data and automatically set the transmission side and reception side. Further, based on the contents of this automatic setting, synchronizing control after the second synchronizing control is performed.