This study examined the effects of concealment on physiological and psychological responses during the Concealed Information Test (CIT). Sixty police officers who volunteered for the study were randomly assigned to either the one non-concealing group (truthful response group) or two concealing groups (“Yes”-only or “No”-only response groups). They underwent the CIT and completed questionnaires about affect and anxiety. Although no significant differences were observed in tonic physiological responses, affect, and anxiety between the non-concealing and concealing groups, the concealing groups had significant differences between critical and noncritical items in skin conductance response (SCR), heart rate, normalized pulse volume, and respiratory speed. In the non-concealing group, only differences in SCR were observed. These results suggested that concealment during the CIT affects phasic physiological responses to stimuli independently of the effect on tonic physiological responses, affect, and anxiety.