Mechanical properties of melt growth GdBa 2 Cu 3 O x (Gd123) superconducting samples with Ag 2 O of 10 wt% and Pt of 0.5 wt% were evaluated at 77 K through flexural tests for specimens cut from the samples in order to estimate the mechanical properties of the Gd123 material without metal substrates, buffer layers or stabilization layers. We discuss the mechanical properties; the Young's modulus and flexural strength with stress-strain behavior at 77 K. The results show that the flexural strength and fracture strain of Gd123 at 77 K are approximately 100 MPa and 1000 μ, respectively, and that the origin of the fracture is defects such as pores, impurities and non-superconducting compound. We also show that the Young's modulus of Gd123 superconductor is estimated to be 160 to 165 GPa.