An apparatus has been developed for the measurement of the permeance (effective permeability–thickness product) of magnetic films for frequencies 1–100 MHz and permeances up to 20 000 &mgr; with an accuracy of ±100 &mgr;. This is suitable for permalloy films in the 0.5–5 &mgr; thickness range, which are used in thin film recording heads operating in this frequency range.