PURPOSE: To promote excavation efficiency by bearing an erector device provided with a segment holding device and a bolt and nut supply device on the front end section of a holder, and providing the segment supply device to the lower part of the holder.

CONSTITUTION: A segment supplied downward of a holder 100 with a segment supply device 200 is turned and provided by means of a holding device 400 of an erector device provided to the front end of the holder 100. After that, the segment 10 is automatically assembled by nuts and bolts fastened to a bolt and nut tightening device through a bolt and nut supply device. In that time, the segment supply device 200, erector device 300, holding device 400 and tightening device 500 used for assembly of the segment 10 are respectively mounted to the holder 100 separated from a shield excavator. According to the constitution, even during the assembly of the segment, reaction force is subsequently taken to the segment to continue excavation of the shield excavator.