The number of noise complaints of Japan is around 15,000 a year and there are about 200 complaints of low frequency noise. In our NPO (Non Profit Organization), the specialists as volunteers on noise, vibration and low frequency noise take counsel with the complaints and measure the low frequency noise. It is difficult to measure the noise in the night by local government, and in such cases we measure the noise in the night for a long-time in complainant's house. However, sometimes we cannot find the appropriate level of low frequency noise, though the complainant appeals for the serious damage by low frequency noise. Therefore we measured the complaint's reaction at the same time with low frequency noise in the complainant's house. We analyzed the correlation between the complaint's reaction and measured low frequency noise. In many cases, we cannot find out the correlation between the measured low frequency noise and complainant's reaction.