PURPOSE: To reduce the inspection time, by judging the connection propriety of an assembly link shaft based on the servo motor current when a moving command is applied to a positioning servo mechanism to move the assembly link shaft mounted at a moving section of a moving mechanism.

CONSTITUTION: When a start switch 30 and a switch 33 are turned ON to start a servo unit 18 and a timer relay 34, a slide base 17 soft starts in the direction B, to shift the shaft 3 of the assembly link shaft comprising a final drive side 1, a surclip 2 and a drive shaft 3 by a value equivalent to play. Unless the movement of the shaft surpasses the play, the motor current (i) exceeds the limit value with increased driving force of a motor 15 but it is continued to be held within the limit value with the action of a current restricting circuit 25 or the like. When the output voltage Vx of a current detection amplifier 31 is larger than a reference value Vr of a decision device 32 at the expiration of the limit time of a relay 34, the connection is judged to be good. When the shaft 3 moves beyond the play value, the voltage Vx becomes smaller than the value Vr, it is to be bad.