Abstract: The width measuring apparatus according to this invention includes a light emitting element, a pair of light receiving elements, a measurement support table for fixing them and calculating device, where a pair of partial laser beams of the laser beam from the light emitting element which are not projected over a traveling elongated object to be measured are received by the light receiving elements, and a width of the elongated object calculated from the received light quantities of the pair of partial laser beams. The width measuring apparatus according to this invention further includes a single light emitting element, pairs of light receiving elements, a measurement support table for fixing and calculating devise, where pairs of partial laser beams of the laser beams from the light emitting element which are not projected over traveling elongated objects are received by the light receiving elements, and widths of the elongated objects are calculated from light quantities of the received partial laser beams.

Abstract: A magnetic recording and reproducing apparatus provided with a magnetic head device comprising a supporting means having a recording magnetic head made of an alloy system magnetic material and a reproducing magnetic head made of a ferrite system magnetic material. The recording and reproducing heads are fixed relative to one another thereby eliminating the need for completely separate head mechanisms and for complex mechanisms to reliably interchange the positions of the two heads relative to the recording medium.