To provide a thermal infrared sensor extremely superior in sensitivity and responsiveness by substantially reducing both transmittance and reflectance by an infrared absorption film and substantially raising an infrared absorption coefficient.
A thermal insulating membrane 4 is formed in the upper surface of a cavity part 6 provided for a silicon substrate 2. A thermocouple 5 for outputting thermoelectromotive force according to temperature changes with the incidence of infrared rays is arranged on the membrane 4. The surface 7a of the infrared absorption film 7 which coats the thermocouple 5 is roughened. The roughened surface 7a of the infrared absorption film 7 is coated with a reflection suppressing film 8 made of a photosensitive organic membrane such as a negative resist material in which an infrared absorption material such as carbon black of approximately 3 wt% is mixed.