PURPOSE: To make it possible to observe a magnetic domain pattern without receiving restriction by the size and shape of a magnetic material, by forming a polymer film of a magnetic powder fixed in said polymer film in a state receiving the influence of a magnetic domain and peeling off the same.

CONSTITUTION: An org. substance such as rubber or plastic is sufficiently dissolved in a volatile solvent and a proper amount of a magnetic powder is added to the resulting solution and sufficiently dispersed therein. The obtained colloidal solution is thinly applied onto a magnetic body having a magnetic domain and sufficiently dried and solidified. Whereupon, the thin film of rubber or plastic is formed onto the magnetic body in such a state that the magnetic powder is taken in said film. Next, the thin film after sufficient drying is peeled off carefully. Then, if this thin film is observed by a transmission type electronic microscope or an optical microscope, the gathering state of the magnetic powder can be observed and the magnetic domain pattern of a magnetic material can be estimated from said state.