We investigated cerebral hemodynamic response during concealment of information about a mock crime using functional near-infrared spectroscopy (fNIRS). Participants either committed a mock crime or not and then were presented with a randomized series of crime-relevant questions and crime-irrelevant questions in a standard concealment task. Participants in the guilty group concealed crime-relevant information about the mock crime but those in the innocent group did not. Recorded fNIRS timeline data sets were analyzed within the framework of a general linear model approach with an adaptive hemodynamic response function. In this analysis, we affirmed that an adaptive temporal parameter in hemodynamic response function during the concealment task differs from a conventionally used temporal parameter. Group analysis showed that the guilty group elicited greater hemodynamic response during the concealment task than did the innocent group. These results suggest that both the frontal cluster, including frontopolar and orbitofrontal areas, and the temporal cluster are involved in concealment. We also identified a potential application for fNIRS to detect concealment in criminal investigations.