To detect a correct rotational position at all times and to halt a cylindrical drum with high rotational accuracy even when there are looseness and play in the rotation transmitting mechanism of the cylindrical drum.

When the cylindrical drum 4 is started to rotate and a magnet 7b comes to a position opposite to an absolute origin position sensor (not shown in Fig.), a pulse counter 15 starts to count the pulses of an absolute encoder 5. On the other hand, the number of pulse count of the absolute encoder 5 when an insertion opening 6 comes directly upward and a magnetic sensor outputs pulses is previously stored. When a halt instruction to halt the insertion opening 6 at a directly upward position is inputted and the present pulse count number approaches a pulse count number corresponding to the halt position, the frequency of a vector inverter 1 is gradually lowered to rotate the cylindrical drum 4 at a very low speed. Then the cylindrical drum 4 is halted when the magnetic sensor is detected.