Abstract: The invention concerns a turntable-using testing apparatus suitable for use in carrying out performance test of, for example, an internal combustion engine. The apparatus has testing units radially arranged on a turntable, each testing unit having a computer, table-side connectors connected to individual computers, a transfer device provided outside the turntable for delivering an object to be tested onto and withdrawing same from one of the testing units, and ground-side connectors connectable to and disconnectable from the table-side connectors and connected to the host computer. The apparatus enables prompt transmission/reception of test data and the like, facilitates correction of troubles and/or failures, and permits mass signal transmission and reception.