PURPOSE: To amplify well outputs from a card insertion detecting magnetic head and a magnetic head for reading magnetically recorded contents with a simple circuit constitution, by connecting both magnetic heads to a single amplifier through analog switches.

CONSTITUTION: Analog switches 5 and 6 are inserted and connected in series to a magnetic head 1 for detecting the card insertion and a magnetic head 2 for reading magnetically recorded contents, and heads 1 and 2 are connected in parallel through analog switches 5 and 6 and are connected to an amplifier 4. When the card insertion is detected by the head 1, only the analog switch 5 is turned on; and when magnetically recorded contents are read by the head 2, only the analog switch 6 is turned on. Output voltages of heads 1 and 2 are amplified successively in the amplifier 4 at different times.