The variations of electronic and magnetic properties of ultrathin Fe overlayers on a W(001) surface as a function of Fe film thickness (1.0-4.0 ML) has been investigated using X-ray magnetic circular dichroism (XMCD) in conjunction with ultraviolet photoelectron spectroscopy (UPS) and low energy electron diffraction (LEED). We found that the ferromagnetic property of Fe film started to build up over 2.0 ML, as we confirmed the spin and angular moment contribution to the magnetic moment using XMCD experiments. We also confirmed that a thermally stable layer is over 2.0 ML of Fe film as we change the annealing temperature taken after Fe deposition at 300 K and at 400 K using UPS. We will systematically demonstrate that the occurrence of ferromagnetic property of Fe film on a W(001) surface is closely correlated to a thermally stable layer of Fe film on a W(001) surface. (C) 2013 Elsevier B. V. All rights reserved.