We investigated the thickness and applied voltage dependences of first and second order magnetic anisotropy, Ku1 and Ku2, respectively, in an ultrathin Fe film. With decreasing Fe thickness, tFe, Ku1 (Ku2) shows a linear increase (decrease) in the range of tFe ≥ 0.46 nm. For tFe ≤ 0.46 nm, however, we observed a clear increase (decrease) of Ku2 (Ku1). In the latter case, Ku1 and Ku2 indicate opposite effect in the voltage-controlled magnetic anisotropy (VCMA), i.e. the anisotropy change in the Ku1 term is partly compensated by that of the Ku2 term. The VCMA coefficient in the Ku1 term reaches −600 fJ Vm‒1 at tFe = 0.40 nm.