To provide a method of constructing an enhanced soil-cement body which improves construction performance and economical performance by performing uniform stirring and mixing even in the case of viscous soil, and an earth auger suitable for the construction.

In the construction of an enhanced soil-cement body using an earth auger, a jet nozzle port 11 for cement-milk injection is provided in an intermediate part of a rod 6 higher than an injection position of cement-milk 13. In addition to stirring and mixing the cement-milk injected from the bit vicinity of an excavation head 4 with present position soil, the cement-milk 13 is also injected aside from the jet nozzle port 11, thereby improving stirring and mixing efficiency. Furthermore, a patch 12 is provided in an injection direction of the cement-milk 13 from the jet nozzle port 11, and an injection range of the cement-milk 13 is limited.