A device for verifying onset of dementia for a subject, the device comprising: an information provision unit having a visual information provision unit capable of providing the subject with one of two alternatively selectable selection items as a stimulus including visual information; an operation unit capable of outputting, in accordance with operation from the subject, a command indicating that one of the two selection items is selected; and a control unit capable of controlling the information provision unit in order to provide the subject with the selection item, and capable of analyzing information for verifying the onset of dementia on the basis of the command input from the operation unit, wherein the control unit has: a stimulus provision unit capable of providing a target stimulus providing one of the two selection items as visual information through the information provision unit a plurality of times, and the stimulus provision unit capable of providing a cue stimulus being visual information instructing one of the two selection items for a preset period through the information provision unit, before providing the target stimuli for each of the plurality of times; a measurement unit capable of measuring a response time from the provision of the target stimulus by the stimulus provision unit to the reception of the command output from the operation unit; an average time computation unit capable of computing an average value of the response times measured by the measurement unit; a storage unit capable of previously storing reference average values previously prepared with respect to a plurality of subjects including a dementia patient and a person other than the dementia patient, the values being average values of the response times to the stimulus provided by the stimulus provision unit; and a data creation unit capable of creating data, in which the average value of the response times obtained with respect to a specified subject by the average time computation unit is compared with the reference average values. an information provision unit having a visual information provision unit capable of providing the subject with one of two alternatively selectable selection items as a stimulus including visual information; an operation unit capable of outputting, in accordance with operation from the subject, a command indicating that one of the two selection items is selected; and a control unit capable of controlling the information provision unit in order to provide the subject with the selection item, and capable of analyzing information for verifying the onset of dementia on the basis of the command input from the operation unit, wherein the control unit has: a stimulus provision unit capable of providing a target stimulus providing one of the two selection items as visual information through the information provision unit a plurality of times, and the stimulus provision unit capable of providing a cue stimulus being visual information instructing one of the two selection items for a preset period through the information provision unit, before providing the target stimuli for each of the plurality of times; a measurement unit capable of measuring a response time from the provision of the target stimulus by the stimulus provision unit to the reception of the command output from the operation unit; an average time computation unit capable of computing an average value of the response times measured by the measurement unit; a storage unit capable of previously storing reference average values previously prepared with respect to a plurality of subjects including a dementia patient and a person other than the dementia patient, the values being average values of the response times to the stimulus provided by the stimulus provision unit; and a data creation unit capable of creating data, in which the average value of the response times obtained with respect to a specified subject by the average time computation unit is compared with the reference average values. a stimulus provision unit capable of providing a target stimulus providing one of the two selection items as visual information through the information provision unit a plurality of times, and the stimulus provision unit capable of providing a cue stimulus being visual information instructing one of the two selection items for a preset period through the information provision unit, before providing the target stimuli for each of the plurality of times; a measurement unit capable of measuring a response time from the provision of the target stimulus by the stimulus provision unit to the reception of the command output from the operation unit; an average time computation unit capable of computing an average value of the response times measured by the measurement unit; a storage unit capable of previously storing reference average values previously prepared with respect to a plurality of subjects including a dementia patient and a person other than the dementia patient, the values being average values of the response times to the stimulus provided by the stimulus provision unit; and a data creation unit capable of creating data, in which the average value of the response times obtained with respect to a specified subject by the average time computation unit is compared with the reference average values.