To provide a fixed azimuth sampling method for sampling soil in a stratum in order to measure the azimuth of the stratum having some depth.

A boring hole 2 is excavated in the ground, and a sampling tube 6 is provided with a mark thereon showing the N-pole on the ground, and plunged into the boring hole bottom, while keeping a state where the mark agrees with the N-pole direction, and the soil is filled into an internal space 7. The sampling tube 6 has a pipe shape having a square section, and rotation or torsion of internal soil at the plunging time is prevented. The azimuth of the filled internal soil is measured by an azimuth sensor 5 provided over the sampling tube 6 and mounted on a boring rod 3.