Considering the noise characteristics of the pump source, the noise spectra of output harmonic field from. the singly resonant frequency doubler is derived by means of the motion equations for SHG. The intensity noise squeezing of 20 % has been measured from the stable SH wave output. (It is in accordance with the squeezing of 30 % if the efficiency of detection system is taken into account). The maximum squeezing measured experimentally is in agreement with the theoretical predictions.