PURPOSE: To print a picture to the same roll photographic paper in an approximately equal picture size, by detecting discrimination signals for full-sized and half-sized negative film picture parts, and converting the magnfication of enlargement of the focused picture.

CONSTITUTION: The picture size discrimination signal for a long-sized film 10 is detected by a picture size detector 14; and if this signal is different from the preceding detected picture size signal, a triadic mirror rotary material 31 is rotated at 45° around the optical axis, and the switching of a movable mirror 27, the alternate switching between lighting circuits for light source lamps 16A and 16B, the size conversion of a negative mask 23, the zoom type switching of a focusing lens 25B, and the switching of the sensitivity of an exposure controlling system after a photodetector 21 are performed. Thus, full-sized and half- sized pictures are printed to the same roll photographic paper in an approximately equal picture size continuously.