A face portion detection device, a behavior content classification device, a speech content classification device, a car navigation system, a face direction classification device, a face portion detection device control program, a behavior content classification device control program, a face portion detection device control method, and a behavior content classification device control method are provided for appropriately classifying a behavior content of the object person from a captured image including the face of the object person. A speech section detection device 1 includes an image capturing unit 10, a data storage unit 11, an image processing unit 12, a lip region detection unit 13, feature extraction unit 14, and a speech section detection unit 15. The lip region detection unit 13 uses a dedicated SVM to detect a lip region from a captured image, and the speech section detection unit 15 uses features of an image of a detected lip region and a dedicated HMM to detect a speech section.