To investigate the relationship between composition and machinability of Fe-Al system intermetallics, orthogonal cutting was performed for some aluminum content of Fe-Al alloy. In the case of small depth of cut, the machined surface of low the aluminum content alloy was smooth, and many cracks were appeared in the high aluminum content alloy. This tendency was more prominent in the case of large depth of cut. Chip shape of the low aluminum content alloy was flow type. However, in the high aluminum content alloy, it was divided into parts finely.