A driver state determination device includes a facial change information acquisition unit acquiring facial change information indicating a time-series change in facial data of a subject, and a driver state determination unit determining the driver state of the subject based on the facial change information. The subject is selected from the group consisting of a subject driving a machine from when brain function activation information that activates human brain function is provided, a subject driving a machine from when the brain function activation information provided to the subject driving the machine is detected, and a subject performing a predetermined operation on a machine.