A brain activity estimating device (10) is provided with: a face skin temperature obtaining means (20); and a brain activity estimating means (30). The face skin temperature obtaining means (20) detects the skin temperature of at least a part of a face of a person, and obtains face skin temperature data including the detected temperature data and position data of the detection part in a time series. The brain activity estimating means (30) estimates the brain activity of the person on the basis of the face skin temperature data obtained by the face skin temperature obtaining means (20). The brain activity estimating means (30) decomposes the face skin temperature data into a plurality of components by means of singular value decomposition, principal component analysis, or independent component analysis. The brain activity estimating means (30) extracts, as a component for determination, a component, the waveform amplitude of which correlates with a change at a time of stability or activation of the brain, from the plurality of components. The brain activity estimating means (30) determines whether the component for determination is related to the brain activity of the person on the basis of whether the temperature of the predetermined part of the face of the person changes.
BRAIN ACTIVITY ESTIMATING DEVICE