The effect of grain size on the tensile strength of Fe-26Mn-2Al alloy has been investigated after changing the microstructure by cold rolling. Microstructures in Fe-26Mn-2Al at room temperature consist of a large quantity of austenite and small quantities of ε and α`martensites. And ε and α`martensites were increased by increasing the degree of cold rolling. With increasing the grain size, the volume fraction of martensite was increased which transformed from the austenite by the cold rolling. While tensile strength was linearly increased with increasing the degree of rolling due to transforming austenite to martensite by deformation, elongation was rapidly decreased at early stage but slowly decreased with increasing the degree of cold rolling. With increasing the grain size, strength and elongation were decreased. This effect of grain size on the tensile strength and elongation is less effective in the specimen cold rolled after solutionizing than the solutionized specimen.