The effect of perpendicular compression on initial susceptibility of polycrystalline soft magnetic materials is investigated. In particular, it is shown that susceptibility magnitude does not decrease immediately with the stress applied. Consequently, a threshold is pointed out below which the domain‐wall susceptibility keeps constant and equal to the initial value. Investigations of this threshold, between room temperature and the Curie temperature (550 K), has allowed a tight connection with intrinsic parameters of the spontaneous domain‐wall arrangement to be established. In order to demonstrate this result, two types of materials have been prepared: perfect materials with domain‐wall configuration approaching ideal orientation and defective materials with randomly dispersed domain‐wall arrangement.