1. A behavior content classification device which classifies a behavior content of an object person based on a captured image including a predetermined portion constituting the face of the object person, comprising: image capturing means for capturing an image including the predetermined portion; feature extraction means for extracting features in an image of the predetermined portion based on a captured image of the image capturing means; an HMM (hidden Markov model) having as input features extracted from an image of the predetermined portion and having as output a likelihood for a predetermined behavior content relating to the movement of the predetermined portion; and behavior content classification means for calculating the likelihood for the features using the features extracted by the feature extraction means and the HMM, and classifying behavior content relating to a movement of the predetermined portion of the object person based on the calculation result.