Properties or thin films of organic dyes prepared under a magnetic held are studied. In spite of the magnetic field strength of 0.1-0.3 T, the effect or the magnetic field was observed in the PL spectra and X-ray diffraction pattern of vacuum-deposited p-quaterphenyl films that show an orientation. The degree of change depended on the magnetic field strength. The phenomenon can be explained by considering that the normal growth of original alignment of p-quaterphenyl molecules due to pi-pi orbital stacking will be disturbed by the irregular orientation due to the magnetic field. On the other hand, this was not observed for diamine derivatives and aluminum quinoline with amorphous film structure.