To provide a soil cement underground continuous wall construction method which enables construction of a good solidification body of a soil cement underground continuous wall in a shorter construction period than a conventional method.SOLUTION: A soil cement underground continuous wall construction method includes: a temporary excavation step of performing excavation while discharging a non-curable injection material from the tip of a single-shaft or multi-shaft column row type construction machine 1, and establishing a wall body made of mixed soil 11 of excavation soil and the non-curable injection material; and a final excavation and solidification step of performing final excavation while discharging and kneading a solidification material slurry to the mixed soil from the tip of a trench cutter type construction machine 2, and solidifying it and constructing a soil cement underground continuous wall 22. The excavation width by a trench cutter type construction machine is equal to or more than an excavation width by a column row type construction machine.SELECTED DRAWING: Figure 1