A mental illness determination device includes a face change information acquisition unit and a mental illness determination unit. The face change information acquisition unit is configured to acquire face change information indicating a time-series change in face data of a subject when emotional stimulation information for stimulating any sense or any combination of senses among an auditory sense, an olfactory sense, a gustatory sense, a tactile sense, and a somatic sensation of the subject to change emotion, and is divided into positive information for increasing comfort and negative information for decreasing comfort is provided to the subject. The mental illness determination unit is configured to determine a state of mental illness of the subject on the basis of the face change information.
