PURPOSE: To protect the end face and light emitting area of a light emitting diode from damage caused by a support tool for the light emitting diode by supporting the diode on three points which are not on the extension of the line of the light emitting areas of the diodes and arranging it on a substrate in a manner in which the line of the light emitting areas and the adjacent line stand in a line.

CONSTITUTION: In a photo-printing head equipped with a substrate 15 and more than one light emitting diode 14 each of which has more than one light emitting area 4 and is arranged in a line on the substrate 15, the diode is supported at least on three points which are not on the extension of the line of the light emitting areas 4 of the diodes 14 and arranged on the substrate 15 in a manner in which the line of the light emitting areas 4 and the adjacent line stand in a line. As a result, both end faces located on the extension of the line of the light emitting areas and the light emitting areas close to the end faces are protected from damage caused by the support.