PURPOSE: To stabilize the connection operation of a sheathing panel and a spindle as a shore in a sheathing structure for excavating a ditch.

CONSTITUTION: A connector 18 with an engaging piece 20 inserted and engaged into the opening 15 of a guide rail 12 for a sheathing panel 4 is inserted to the outer end of a spindle 13, and a cotter 28 is put into the slots 26, 25 of the connector and the spindle. An engaging finger section 28b under an inverted state is formed at the front end of the cotter 28, and the engaging finger section 28b is engaged with the inner end 18a of the connector 18 before insertion operation into the opening 15 of the engaging piece 20. Accordingly, the sinking of the connector 18 into the spindle 13 is prevented.