Abstract: To set the drop-out detection level constant in the drop-out detecting circuit used for a magnetic recording apparatus, without regulating the output level of a magnetic recording head and the gain of a preamplifier, the detecting circuit comprises an envelope detection section for detecting the envelope of a reproduced signal; a voltage division section for dividing the output signal voltage of the envelope detection section; and a comparator for comparing the output signal of the voltage division section with the reproduced signal to detect a drop-out of the reproduced signal. Therefore, it is possible to reduce the number of parts and the number of adjustment process to reduce the manufacturing cost thereof. Further, to detect the drop-out portion throughout as defective tape locations, irrespective of the length of the drop-out portion, the detecting circuit further comprises a drop-out start detection section, a drop-out end detection section, and an OR gate.