Independent component analysis (ICA) is a method separating the mixture of signals into statistically and mutually independent ones. It has been applied to not only the Cocktail-party problem but also EEG analysis using the EEG waveform, digital signal processing, image processing and cognitive technique field actively. This study aims to propose a procedure to estimate the modal responses and mode shapes of a structure by using the ICA method from analyzed responses of the structure, which is first attempt to the architecture and civil engineering works field. It is introduced a basic concept of ICA with the fixed-point (FP) algorithm based on secant method and the kurtosis. From the concept of the separation performance of mixed-signal, modal responses and mode shape of a building structure are estimated based on ICA method. For the verification of the ICA method, a numerical simulation is performed. In the simulation, it is assumed that the mode shape and time history of the structural responses had been known through the dynamic analysis and state space analysis of a structure. Then, some parts of responses of the structure are chosen from analysed responses and those are used as input responses to estimated the modal responses and mode shape of a structure by the ICA method. From the numerical results, it is shown that the ICA method can be effectively applied to the mode separation and the estimation of modal properties of structure.