PURPOSE: To apply interactive control to plural control elements at a high speed with high reliability in a preferable way by arranging a microprocessor- based local control circuit to each of the plural control elements.

CONSTITUTION: Control elements 12, 14, 16, 18, 20 have respectively local control circuits 22, 24, 26, 28, 30 which are identical circuits to each other, and each local control circuit includes a microprocessor 32, a local bus 34, a dual port message RAM 36, and a broadcast circuit 38. Then a message is sent from the broadcast circuit 38 via a system bus 40 to the local control circuit and written in all message RAMs 36 simultaneously. Thus, the plural control elements such as an actuator 12, a position transducer 16, a load transducer 14 and distortion transducers 18, 20 of a material test load frame are controlled at a high speed.