A surface flaw model is proposed. The model describes the magnetic field topography H d for normal magnetization by an alternating field H ω of frequency ω. It is shown that H d can be presented as two cofactors: one cofactor describes a dependence of the topography on coordinates x, z and parameters of a flaw (depth h, opening width 2b), and another cofactor describes its dependence on the electrophysical properties of a tested material containing the surface flaw (specific conductivity σ, and the relative magnetic susceptibility μ). Transition from the magnetostatic field of a flaw ω = 0 to a quasi-stationary field for magnetization under an alternating field H 0s of frequency ω is carried out using the model proposed for the magnetic field of a surface flaw under normal magnetization.