To provide such a precast concrete underground structure with high rigidity and earth pressure resistance force as being capable of easily mounting a jack for settlement and easily apply an earth anchor for taking measures for buoyancy after completing the structure.

In a construction method for a precast concrete underground structure, a wall 1 is formed by assembling plural precast concrete split walls 2 consisting of upper end ribs 2a, wall bodies 2b and lower end ribs 2c. The split walls 2 are inserted into an earth anchor 10 which is previously set up in prescribed place to assemble the plural split walls 2, and then a tendon 6a is horizontally inserted between the split walls 2 and tensely fixed thereto to integrate the plural split walls 2 for constructing the wall 1. The earth anchor 10 is tensed by a jack 11 arranged on the wall 1 to settle the wall 1 while excavating the inside of the wall 1. Then, a bottom 9 is constructed by reinforcing concrete placed at a site, the earth anchor 10 is fixed to the wall 1 and a precast concrete first-floor plate is mounted on the wall 1.