PROBLEM TO BE SOLVED: To easily and quickly install the field shear tester by decreasing factors which gives bad influences on the measuring accuracy.
SOLUTION: A bottom shear box 3 is guided and supported in the horizontal direction by the guide support frame portion 6, a top shear box 4 is fixed and installed to a guide support frame portion 6 with a gap provided by a top and bottom adjusting and fixing means 14 so as to avoid its contact with the bottom shear 3, a shear force loading means 17 is installed by connecting the shear box 3 to a horizontal reaction support frame portion 7, and a vertical force loading means 29 is installed to a vertical force loading frame 27 which is bolt-connected to a vertical frame portion 8. In the condensation process, the bottom shear box 3 and the top shear box 4 are fixed in a tight adhesion state with a locking bolt 16, and the sample of specimen 1 is never leaked out from every shear boxes 3 and 4. In the shearing process, the locking bolt 16 is taken out, the top shear box 4 is raised to a predetermined distance with the top and bottom adjusting and fixing means 14, and a gap is provided between the top and bottom shear boxes. The shear force loading frame 5 is formed to a rectangular shape by bolt connection, and a construction which can be assembled and disassembled can be formed.