A measurement element includes a semiconductor substrate with electrical insulating film formed thereon. A resistor formed on the electrical insulating film constitutes a heater; and a cavity is formed by removing a portion of the semiconductor substrate that corresponds to a region where a body part of the resistor is formed. The region where the body part of the resistor is formed is formed into a thin wall part by the cavity, and an opening and a slit is formed in a portion of the thin wall part in such a manner as to penetrate the thin wall part in the thickness direction. The measurement element has a film formed covering the region of the opening or slit.