Self assembled (In1-xMnx)As diluted magnetic semiconductor quantum dots (QDs) were grown on GaAs(100) substrates by using molecular beam epitaxy with a goal of producing (In1-xMnx)As QDs with a semiconductor phase and a high ferromagnetic transition temperature (T-c). High-resolution transmission electron microscopy measurement,; showed that crystalline (In0.84Mn0.16)As QDs were formed on GaAs substrates. Magnetic force microscopy images showed that the formed QDs were symmetric single-domain particles. The magnetization curve as a function of the magnetic field at 5 K indicated that the (In0.84Mn0.16)As QDs were ferromametic. and the magnetization curve as a function of the temperature showed that he T, was as high as 400 K. These results indicate that (In0.84Mn0.16)As QDs grown on GaAs(100) substrates hold promise for potontial applications in quantum bit devices operating at room temperature. (C) 2003 Elsevier B.V. All rights reserved.