A new method for measuring the three-dimensional magnetic stray fields extending beyond a magnetic head is presented. The electron beams are injected to the head surface, and the positions of the reflected electron beams are measured at the detecting plane placed above, and in parallel with the head surface. The three-dimensional magnetic fields are reconstructed using an algebraic reconstruction technique (ART) algorithm from the deflection vectors of the reflection electron beams which are deflected by the magnetic fields. Our measurement system was applied to the measurement of the field distribution of an erasing head for a video cassette recorder. From these results, the applicability of our method for measuring magnetic stray held distribution near the head surface is clarified.