a paper supplying deck is insertable into and withdrawable from a paper supplying portion of a body resulting in electrical connection between the side of the paper supplying deck and the side of the body through a drawer - type connector when the paper supplying deck is inserted and interruption of such electrical connection when the drawer is withdrawn . the paper supplying deck has a paper carrying portion with a paper width setting mechanism and a variable resistor the resistance value of which is changed in dependence on the paper width setting mechanism , thereby changing an output paper width detecting voltage . on the wide of the paper supplying deck , a resistance which prevents the paper width detecting voltage from amounting to a power source voltage even though the resistance value of the variable resistor reaches a maximum value , is connected in series with the variable resistor . on the side of the body , a pull up resistance is connected with the connector to discriminate between voltages in the connector when the paper supplying deck is mounted and when the paper supplying deck is not mounted .