PURPOSE: To prevent a malfunction even when a surge signal mixes, and to read the angle of revolution accurately by using a multiple division BCD output system absolute position divider and outputting a large number of code signals in a rotary press.

CONSTITUTION: What there is a register mark between predetermined addresses, gate signal setters 57, 58 for a sub-controller 48 are each set, and a MPU56 reads the set values, and outputs several gate sinal to comparators 54, 55. When a large number of code signal data in an absolute position divider 47 connected to a plate-cylinder driving shaft coincide with the setting signals by the comparator 54, a Q output from a flip-flop 59 reaches to H, and register mark pulses from a scanning head 10 are outputted through an AND 53. When the data coincide with the setting signals by the comparator 55, the Q output reaches to L, and the output is stopped. Accordingly, a rotary press does not operate by mistake even when surge signals mix, and the correct angle of revolution can be read at all times even when the rotary press returns from temporary service interruption.