An on-site measurement system of low frequency noise (LFN) and annoyance response to lowfrequency noise was developed to find the reasons why people suffer from environmental noise with low frequency component. The advantage of this system is that we can easily find the relationship between complainants' subjective responses to acoustical events in dwellings and their physical properties such as time trend and frequency characteristics. Measurements were conducted with the developed system in residential houses and responses of complainants were also collected using a switch box during measurements. The system is capable to do FFT and 1/3 octave band analysis for five channels with enough frequency resolution. Four analysis channels were used for interior noise measurement and the rest was for outdoor measurement. Additional sound level meter with real-time 1/3 octave band analyzer was also used. Complainants were asked to operate switches when he/she detected the beginning and the end of the target noise during the measurement. This paper explains the developed system and an example of measurement result.