We have studied the influence of As flux on InAs nanostructures on GaAs (211)B surfaces grown by molecular beam epitaxy (MBE) at various growth temperatures (T-S). It is shown that isotropic quantum dots (QDs) are formed at low Ts under high As pressure condition. However, non-isotropic nanostructures, quantum dashes (QDHs), are formed under low As flux conditions. It is also shown that the sizes of nanostructure become larger with increasing T-S. The shapes of nanostructure depend on As flux as well as T-S.