1. A display device comprising:
a display panel body that has a display surface emitting light; and
a brightness sensor unit that is fixed on the display surface of the display panel body,
wherein the brightness sensor unit includes: a brightness sensor detecting a brightness of the light from the display surface;
and a sensor holder comprising a light transmissive material,

the sensor holder includes: an adhesion surface adhered to the display surface of the display panel body; and a light diffusing
portion diffusing the light from the display surface,

the brightness sensor is fixed to a position facing the display surface with sandwiching the light diffusing portion of the
sensor holder between the brightness sensor and the display surface,

wherein the sensor holder includes a base portion in which a housing cavity housing the brightness sensor is formed, and the
light diffusing portion is provided on an inner surface of the housing cavity, the inner surface opposing the brightness sensor.