PURPOSE: To enable stable photoengraving by measuring directly the etching condition in the pattern part of a gravure cylinder under etching, calculating relationally the same with a reference etching value for the pattern density of a positive film and controlling etching conditions at all times.

CONSTITUTION: The respective etching conditions of the light part, medium contrast part and shadow part of the pattern parts 21W24 of a gravure cylinder 20 are detected by detecting means 30W32 and the detected signals are inputted to a control device 40. On the other hand, a rotary encoder 50 is attached to the cylinder 20 and one point in the pattern part to be detected by the means 30W32 is assigned by the signal from the encoder 50. The etching conditions are calculated according to the detected signals in the device 40 and are calculated relationally with the predetermined reference etching value of a positive film. The results thereof are inputted to an etching device 60, by which the etching conditions are controlled at all times. The stable photoengraving is thus accomplished.