PURPOSE: To facilitate the test of a head and to decrease the interference of signals and a number of components by transferring a part of a voltage generated by a test write signal to a reading circuit in a recording head.

CONSTITUTION: A testing or recording/writing signal is sent from a writing circuit 16 through a magnetic head 8. A write signal is successively made access by transferring a small part of the voltage of a head 8 through a resistance circuit of a loop back circuit 20 coupled to the input of an amplifier of a reading circuit 18. The accessed signal is processed so as to include at least one detectable peak by means of the loop back circuit 20. In order to inspect the function of the writing circuit 16, the reading circuit 18 and the read/write magnetic head 8, the generated read signal is inspected by comparing the generated signal with an original test signal recorded in the head 8.