A physiological state determination device (500, 600, 700) for determining a predetermined physiological state of a subject, the physiological state determination device comprising: a brain function activation information detection unit (541, 641, 741) configured to detect brain function activation information corresponding to the physiological state; a face change information acquisition unit (542, 642, 742) configured to acquire face change information indicating a time-series change in face data of the subject; and a physiological state determination unit (545, 645, 745) configured to determine the predetermined physiological state of the subject on the basis of the brain function activation information and the face change information, wherein: the predetermined physiological state is a degree of concentration; and the brain function activation information detection unit includes a specific operation detection unit (541a, 741a) configured to, when a specific operation is performed on a predetermined device by the subject or a measuring person other than the subject, determine that a brain function activation stimulus is provided to the subject and detect the brain function activation information, the specific operation being an operation of inputting an operation instruction presentation command, the brain function activation information being an operation action, the brain function activation stimulus being an instruction of the operation action. a brain function activation information detection unit (541, 641, 741) configured to detect brain function activation information corresponding to the physiological state; a face change information acquisition unit (542, 642, 742) configured to acquire face change information indicating a time-series change in face data of the subject; and a physiological state determination unit (545, 645, 745) configured to determine the predetermined physiological state of the subject on the basis of the brain function activation information and the face change information, wherein: the predetermined physiological state is a degree of concentration; and the brain function activation information detection unit includes a specific operation detection unit (541a, 741a) configured to, when a specific operation is performed on a predetermined device by the subject or a measuring person other than the subject, determine that a brain function activation stimulus is provided to the subject and detect the brain function activation information, the specific operation being an operation of inputting an operation instruction presentation command, the brain function activation information being an operation action, the brain function activation stimulus being an instruction of the operation action. the predetermined physiological state is a degree of concentration; and the brain function activation information detection unit includes a specific operation detection unit (541a, 741a) configured to, when a specific operation is performed on a predetermined device by the subject or a measuring person other than the subject, determine that a brain function activation stimulus is provided to the subject and detect the brain function activation information, the specific operation being an operation of inputting an operation instruction presentation command, the brain function activation information being an operation action, the brain function activation stimulus being an instruction of the operation action. the specific operation being an operation of inputting an operation instruction presentation command, the brain function activation information being an operation action, the brain function activation stimulus being an instruction of the operation action.