To provide an air pressure sensor unit and an air pressure display device provided with a light emission display means allowing a person on the outside of a vehicle to visually recognize air pressure of a tire at one glance, even when the vehicle is traveling, or in a dark night periphery or the like, or viewed from a far position.

The air pressure sensor unit 2 is installed on a wheel of the vehicle, detects the air pressure of the tire and visually displays the state of the air pressure of the tire (T). The air pressure sensor unit 2 has a pressure sensor for detecting the air pressure of the tire; a light emission display means (21c) provided on a surface at the outside of the vehicle of a central part of the wheel; and a light emission control means (CPU) for controlling the light emission of the light emission display means (21c) based on the air pressure of the tire detected by the pressure sensor.