In order to investigate the mechanical properties of Gd123 single-grain bulk superconductors fabricated using a modified QMG method, tensile tests in the direction of the a/b-or c-axis of small specimens cut from bulk samples have been carried out at 293K. As for the mechanical properties perpendicular to the c-axis, there was no significant difference between those in the crystal growth direction and those perpendicular to it. While the average value of Young's modulus of the bulk sample with 33.0mol%-Gd211 particles, 118GPa, was higher than that of the bulk sample with 28.7mol%-Gd211, 111GPa, the average value of the tensile strength of the former, 36MPa, was lower than that of the latter, 40MPa. Tensile strength and Young's modulus in the c-direction, 10MPa and 37GPa, were quite low compared with those mentioned above. Poisson's ratio based on the transverse strain parallel to the c-axis, 0.15, was significantly smaller than that perpendicular to it, 0.30. In the specimens with higher length, however, the difference was decreased to some extent. With regard to the anisotropy of the Poisson's ratio, the effect of a microcrack opening in the c-axis direction was discussed coupled with the constraints at the interface of the specimen with the sample holder.