To provide a soldier pile lagging method capable of processing subsoil water or the like capable of being executed for constructing an earth retaining wall in the case the ground is excavated.

The ground aiming for excavations is excavated, and a sheet pile is inserted between soldier piles with the advance of the excavations to carry out earth retaining. When the excavations reach a subsoil layer, the excavated bottom around the exposed subsoil water layer is only precedently excavated, and a water permeable sheet is provided to the excavated side face under the subsoil layer. The sheet pile is inserted between the soldier piles to support the water permeable sheet, and the front of the sheet pile is covered with a water stoppable sheet. It is constituted that the subsoil water is led to a catch pit formed downward of the sheet pile from the water permeable sheet placed to the back of the sheet pile, and the subsoil water led to the catch pit is pumped up. With the advance of the excavations, the constitution leading the subsoil water to the catch pit formed downward of the sheet pile from the water permeable sheet placed to the back of the sheet pile is gradually replaced, and the excavations are carried out up to the depth of the final excavated bottom while pumping up the subsoil water led to the catch pit.