PURPOSE: To prevent damage of a tape by using two output signals with differ ent phases obtained from a detector to discriminate the rotation direction of a reel and stopping the tape running when the reel is driven in a direction different from a desired reel rotation direction.

CONSTITUTION: A magnetic substance 3 is formed on a bottom face of a reel turntable 5 and Hall elements 1, 2 placed sufficiently closely thereto detect the magnetic flux of the magnetic substance 3. An output from the Hall elements 1, 2 connects to an input D of a D-FF circuit 4 and a clock input respectively. The two Hall elements fitted to have a phase difference of 90° from each other detect the polarity of the magnetic substance and the outputs of the two Hall elements are used for the clock input and the D input of the D-FF 4, then the rotation direction of the reel is discriminated, the output of the D FF is fed to a control circuit block, where the tape running stop is commanded if the real rotation direction of the reel differs from the desired rotation direction.