We have investigated Mn atoms on a GaAs(110) surface prepared by molecular beam epitaxy. Atomic-scale local structures have been observed at the temperature of 200 degrees C: single Mn atom and double Mn atoms exist in Ga row on scanning tunneling microscope (STM) images. We also show simulated STM images of Ga-substituted Mn atoms of GaAs(110), calculated from the first-principles calculations. Both experimental and theoretical STM images of single and double Mn configurations are in good agreement with each other. Therefore, the Mn atoms seems to be incorporated into the topmost Ga site due to STM images. (c) 2013 Elsevier B.V. All rights reserved.