To improve the efficiency of earth retaining work by providing a length adjusting part in one end of an elongation/contraction operation part elongated/ contacted in its longitudinal direction by a hydraulic pressure and a manual hydraulic pump in the other end for supplying a hydraulic pressure to the elongation/contraction operation part by manually producing a hydraulic pressure.

A sheet pile 21 is vertically adhered to the opening part of a ground 23 and a sheet pile 22 is vertically adhered to the opening part of a ground 24. Then, the engaging part 16 of an earth retaining device 11 is engaged with the upper end of the sheet pile 21 and an engaging part 15 is engaged with the upper end of the sheet pile 21. In this case, a length is adjusted by a length adjusting part 13 extending a rod and the side faces of the engaging parts 15 and 16 are adhered to the inner surface of the sheet piles 21 and 22. Then, by moving the handle of a manual hydraulic pump 14 up and down, pressure oil is produced and, by supplying the pressure oil to an elongation/contraction operation part 12, the elongation/contraction operation part 12 is extended. Then, since both ends of the earth retaining device 11 are expanded, an interval between both side faces of the engaging parts 15 and 16 is expanded, the sheet pile 21 is pushed by the engaging part 16 and the sheet pile 22 is pushed by the engaging part 15.