To achieve high accuracy at the time of setting a picture to a plate even under a disadvantageous condition.

A clock generator 11 generating a clock signal for a picture setting device which transfers picture setting information to a rotating plate 1 has an input part 14 to which an actual value signal depending on the angular position of the plate 1 is applied and an output part 15 from which the clock signal is outputted and, moreover, has a first comparator 19 which is provided with a first input part to which the actual value signal is applied as an analog signal and a second input part to which an analog target value signal expressing the target value of the angular position of the plate 1 each time is applied. A clock signal which is generated according to the compared result of the analog target value signal and the analog actual value signal is outputted at the output part of the first comparator 19.