PURPOSE: To attain a high-linearity sensor by suspending a weight inclinably in a box body and arranging a magnet and a Hall IC on both sides of the weight so that they face each other.

CONSTITUTION: A tilt angle sensor is provided with a box body 11 and a flat spring 13 which has one end fixed to a ceiling face of the box body 11 and has a weight 12 fixed to the lower part in the suspending state. Magnets 14 and 14' are buried on both sides of the weight 12 in the inclination direction. Hall ICs 15 and 15' are arranged on the inside wall face of the box body so as to face magnets 14 and 14'. Hall ICs 15 and 15' are connected in anti-series, and the differential output is amplified by an amplifier 16 and outputted as a tilt angle detection signal of an object 10 to be measured.