In this study, we extracted brain activities related to semantic relations and distances to improve the precision of distance calculation among concepts in the Associated Concept Dictionary (ACD). For the experiments, we used a multi-channel Near-infrared Spectroscopy (NIRS) device to measure the response properties of the changes in hemoglobin concentration during word-concept association tasks. The experiments’ stimuli were selected from pairs of stimulus words and associated words in the ACD and presented in the form of a visual stimulation to the subjects. In our experiments, we obtained subject response data and brain activation data in Broca's area ―a human brain region that is active in linguistic/word-concept decision tasks― and these data imply relations with the length of associative distance. This study showed that it was possible to connect brain activities to the semantic relation among concepts, and that it would improve the method for concept distance calculation in order to build a more human-like ontology model.