To provide a tire pressure detection device, wherein durability of a pressure sensor is enhanced.

This tire pressure detection device 1 is equipped with a bottomed box-shaped case 4, a circuit component 5 group, including the pressure sensor 3 and a quartz oscillator 14 mounted on the inner bottom surface 4b of the case 4, a cover 6 for covering an opening 4a, and a sealing member 7, formed by hardening a silicon resin filled from the inner bottom surface 4b to a prescribed height position in the case 4, and is used by being mounted on a vehicle tire. A space, existing between the sealing material 7 and the cover 6 in the case 4, is a communicating space 8 that communicates with the air in the tire through an air hole 6a of the cover 6. The pressure sensor 3 is a capacitance pressure-sensitive element, and a diaphragm 12 is held on a silicon substrate 9 loaded on the inner bottom surface 4b, and the height position of the sealing material 7 inside the case 4 is set approximately equal to the height position, where the diaphragm 12 exists.

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