To make the finishing of a copied image almost constant regardless of a change in a copying environmental condition with the lapse of time.

After a specified time lapses from the setting of a reference copying condition (260 Yes), a condition setting image is copied on a photographic printing paper and the density of the condition setting copied image formed on the photographic printing paper is measured (266). The change in color and density from when the reference copying condition is set is calculated (268) and the time when the change in the color or density of the condition setting copied image reaches a threshold limit value is predicted with the result of the calculation (274). When the predicted time is obtained (276 Yes), the condition setting image is copied on the photographic printing paper, the density of the condition setting copied image formed on the photographic printing paper is measured and a copying condition correction value is set with the result of the measurement (282). Further, the change in the color and density in this time is calculated (288) and the time when the change in the color or density reaches the threshold limit value next is predicted in consideration of the deviation between the change in the color and density in this time and the threshold limit value (288).