A planar imaging technique of laser-induced fluoresecence is applied to the measurements of nitrogen monoxide in methane-air stoichiometric premixed laminar flames of small scale. Laser sheets of P_11(36.5) excitation line at 225.178nm is used. Intensity maps of fluorescence lines about 247nm are recorded through an interference filter (246.8nm, FWHM 14.6nm) by an intensified CCD camera. This specific excitation line can provide an approximately linear relation between fluorescence intensity and concentration of nitrogen monoxide in temperature range of 1000 - 2000K. Relative concentration maps are obtained. Temperature is determined computing the equations of fluorescence intensity and data of energy levels. The results of this thermometry are compared with those of Rayleigh scattering method. The Rayleigh scattering intensity for the methane-air stoichiometric flame is inversely proportional to the absolute temperature. The comparison gives a good agreement. This LIF measurement techniques demonstrate a possibility of application to practical measurements of larger size industrial burner for evaluating NO_x emission levels.