PURPOSE: To enable the printing of a mark in a desired color by providing a plurality of light sources with a different wavelength and a plurality of light guide means for addition maxing of the color lights in a side printer for color photographic films.

CONSTITUTION: A color photographic film 1 is transferred along a print roll 2 and a control section 4 checkes positional information on a pulse of a pulse generator 3 to feed a mark generation signal to a light source section 5, which comprises light emitting diodes 6aW6g, 7aW7g and 8aW8g respectively in red, green and blue and divided into 7 groups, the same group, for example, those 6a, 7a and 8a emits light simultaneously. These lights mixed passing through light guide means 10W16 and form an image on a color photographic film 1 with a lens 18. This also enables the side printing of a color mark in a desired color by adjusting the ratio of three color light components.