Infrared face image data is obtained (11) on a person (P) who is a subject of discrimination using an image signal (VDA) from a television camera (2A); the cheek region and jaw region temperatures of the subject (P) are sampled based on the infrared face image data; the averages of the temperatures are calculated (15, 16); cheek data/jaw data is calculated (17); and a cheek emphasized variance value is calculated (18). The cheek data/jaw data and cheek emphasized variance value are mapped on an XY plane (19), and gender discrimination of the person (P) is conducted based on the result. In addition, gender discrimination is conducted using the cheek data/jaw data (21) and gender discrimination is conducted using the cheek emphasized variance value (22), and gender identification is conducted in accordance with agreement between two or more of the multiple gender discrimination results (24).