Photoelectric observations were made of four N stars (HD 51208, HD 75021, V 1942 Sgr, and RU Vir) at careful1y chosen discrete wavelengths between $7000{AA};and;11000{AA}$ with $30{AA}$ bandpass width. Their effective temperatures have been derived by fitting the black-body radiation curve to the observed continuum intensities at $7800{AA},;9000{AA};and;10800{AA}$. The resulting temperature ranges from $2500^{circ}K;to;2900^{circ}K.$. It is probable that almost all the N stars belong to this range of temperature. However, the temperatures of very red N stars can not be well determined due to large variability and redistribution of their radiation energy arising from the graphite shells around them.