In this study, our purpose is the development of measuring and monitoring system to investigate the brain activity in usual behavior without restraint. Using this system, we can obtain physiological information such as EEG, ECG and cerebral blood of the subject always and anywhere, even if subjects walk around or move freely. In this study, we applied this system to evaluate the concentration state of the child with special needs. We invited a 10-years-old-boy with mental retardation to cooperate in our study, and measured the EEG, ECG, NIRS and moving activity while he was in education program for 30 minutes. EEG electrodes were placed according to international 1020 system at Fz (frontal cortex) and Pz (parietal cortex). The hemodynamic response was also measured at the forehead by NIRS. At the same time, we measured the electrocardiograph(ECG). After removing the body movement artifact from the EEG data, we analyzed the time-frequency response of EEG. As a result, we observed differences in the time-course of EEG power at alpha band (812 Hz) and theta band (1320 Hz), between the concentrating-state (studying) and rest-state.