To provide a luminance detector for detecting luminance of an optional region on a panel.

The luminance detector includes a base part, a first shaft, a first actuator, a second shaft, a second actuator and at least one luminance sensor. The first shaft is pivoted to the base part, and the second shaft is pivoted to the first shaft. The luminance sensor is disposed on the second shaft. The first actuator is used to operate the first shaft to rotate relative to the base part, and the second actuator is used to operate the second shaft to rotate relative to the first shaft. In this manner, the luminance sensor on the second shaft can detect luminance of an optional region on the panel. Luminance on the panel can thereby be uniformly calibrated.