The effects of grain size on the stress-strain characteristics of Cu-Al-Mn-based pseudoelastic (PE) sheet specimens with various relative grain sizes d/t (d=grain size, t=sheet thickness) were investigated using cyclic tensile testing. The stress-strain characteristics such as the yield stress σ y , work-hardening rate dσ P E /dε and stress hysteresis of pseudoelasticity Δσ decreased, and the obtained maximum PE strain ε P E M A X increased with increasing d/t. The σ y , dσ P E /dε, Δσ and ε P E M A X plots as a function of d/t were divided into three regions. The critical points dividing the plots into the three regions were located at d/t~1 and d/t~2. These results can be explained from the standpoint of constraints between grains, depending on grain structure such as a fine equiaxed grain structure, a columnar-like grain structure and a fully columnar grain structure.